No evidence for increased fitness of offspring from multigenerational effects of parental size or natal carcass size in the burying beetle Nicrophorus marginatus

Ethan P Damron; Ashlee N Smith; Dane Jo; Mark C Belk

doi:10.1371/journal.pone.0253885

. 2021 Jul 7;16(7):e0253885. doi: 10.1371/journal.pone.0253885

No evidence for increased fitness of offspring from multigenerational effects of parental size or natal carcass size in the burying beetle Nicrophorus marginatus

Ethan P Damron ^1,^#, Ashlee N Smith ^1,^‡, Dane Jo ^1,^‡, Mark C Belk ^1,^*,^#

Editor: William David Halliday²

PMCID: PMC8263245 PMID: 34234367

Abstract

Multigenerational effects (often called maternal effects) are components of the offspring phenotype that result from the parental phenotype and the parental environment as opposed to heritable genetic effects. Multigenerational effects are widespread in nature and are often studied because of their potentially important effects on offspring traits. Although multigenerational effects are commonly observed, few studies have addressed whether they affect offspring fitness. In this study we assess the effect of potential multigenerational effects of parental body size and natal carcass size on lifetime fitness in the burying beetle, Nicrophorus marginatus (Coleoptera; Silphidae). Lifespan, total number of offspring, and number of offspring in the first reproductive bout were not significantly related to parental body size or natal carcass size. However, current carcass size used for reproduction was a significant predictor for lifetime number of offspring and number of offspring in the first brood. We find no evidence that multigenerational effects from larger parents or larger natal carcasses contribute to increased fitness of offspring.

Introduction

Multigenerational effects (often called maternal effects) are components of the offspring phenotype that are the result of the parental phenotype and the parental environment as opposed to heritable genetic effects [1–4]. These effects are widespread in nature and have been extensively studied in invertebrates [3, 5–8]. Multigenerational effects have been reported in response to such factors as nutrients, egg size, the presence of predators, maternal age, maternal body size, and disease resistance [6, 9–12]. The phenotypic changes that occur in offspring as a result of multigenerational effects include, changes in body size, age at maturity, developmental rate, dispersal behavior, survival, lifespan, and diapause [13–22]. Such traits are often assumed to contribute to evolutionary fitness of offspring, but tests of this connection are few.

One of the most frequently reported multigenerational effects is variation in body size. Body size is well studied because of its strong, positive relationship with fitness in some species [23–25], and because an individual’s size is typically easy to measure. Parental body size has been shown to cause multigenerational effects in offspring where larger females lay larger eggs [11, 26–32], which then hatch into larger offspring. Natal environment can also cause multigenerational effects on body size. On poor quality food resources, females tend to lay fewer, but larger eggs [9, 33, 34]. There is also a positive correlation between resource availability and offspring size [35, 36]. In crowded environments with more competition for resources, females tend to lay fewer, larger eggs, which theoretically gives offspring a size advantage when competing for resources [37–40]. Although there is ample evidence for multigenerational effects on offspring body size, it is unclear whether those differences in body size of offspring translate into increased fitness of offspring.

The overall fitness of an individual can be measured as the total number of offspring produced over a lifetime [41, 42]. Estimating fitness in natural populations is difficult [43–46], and many researchers use phenotypic traits such as body size, ejaculate size, and egg load as predictors of lifetime fitness [35, 47–49]. However, the link between these measures and lifetime fitness is often assumed, but not usually empirically tested (i.e., [50–52]). Increased offspring body size resulting from multigenerational effects does not necessarily lead to an increase in fitness of offspring [4, 53]. Hence, the need to examine the relationship between multigenerational effects and resulting fitness empirically.

Burying beetles (genus Nicrophorus) are ideal organisms for studies of multigenerational effects of body size. These beetles use small vertebrate carcasses for food and reproduction, and the carcass serves as the sole food resource for both parents and offspring during reproduction [33], thus effects of parental size and natal carcass size can be disentangled. The parents provide their offspring extensive parental care in the form of regurgitating predigested carrion and defending the larvae from intruders [54, 55]. Adult body size is determined by the amount of carrion that an individual consumes as a larva, and parents cull the brood through filial cannibalism so that the brood size matches the size of the carcass [33, 56], resulting in a positive correlation between offspring number and carcass size [33, 39]. In at least one species, parents also cull the brood according to their competitive environment so that they raise fewer, larger offspring when competition for carcasses is high, and more, smaller offspring when competition is low [39]. Body size is important for competitive interactions because inter- and intraspecific competition for carcasses can be intense [57–60], and body size generally determines the winners of competitions in both males and females [35, 57, 61–65]. However, the importance of body size to fitness is poorly known in most species of burying beetles (see [33, 65]).

Previous studies in burying beetles have demonstrated multigenerational effects on offspring body size. For example, larger offspring being produced on larger carcasses [33, 65], larger mothers laying larger eggs, which hatch into larger offspring [11], young mothers producing smaller offspring [66], mothers producing smaller offspring when the male parent is present [52], mothers altering hormone concentration in eggs [67], and mothers changing egg laying and offspring care behaviors when deprived of food [68]. Body size of the parent and carcass size are dominant mechanisms through which multigenerational effects are transmitted in burying beetles. Parents control the size of offspring on a carcass in two ways. First, by culling first instar larvae parents that leave fewer offspring on a carcass will produce larger offspring [56]. Second, parents consume a certain portion of the carcass for themselves, thus parents that consume less of the carcass can produce larger offspring on a given carcass size [33, 39]. Larger carcasses provide more resources for both parents and their offspring, thus larger carcasses often result in larger offspring [33]. Clearly, multigenerational effects on offspring size in burying beetles may be transmitted through both parental size and carcass size (i.e., natal environment). The implied prediction is that these multigenerational effects are anticipatory and adaptive such that larger offspring would produce more offspring over their lifetime and thus express increased fitness [4]. However, multigenerational effects may not be adaptive for offspring, rather they can evolve only to increase fitness of the parents [4]. Whether multigenerational effects on body size in burying beetles are adaptive for offspring and translate into increased fitness of offspring is not known.

In this study we tested whether multigenerational effects of parental size and natal carcass size that result in increased offspring size in the burying beetle Nicrophorus marginatus [65] also cause an increase in lifetime fitness of offspring (i.e., they are adaptive [4]). We use a two-generation experimental design combined with a measure of lifetime fitness to assess possible fitness effects transmitted through parent body size or quality of natal environment.

Methods

Source of burying beetles

To generate the laboratory-bred population to use for the experiment, we captured adult N. marginatus at the Utah Wetland Preserve near Goshen, Utah, USA (this is public land, and no permits were required to trap or collect beetles), in August 2014 using pitfall traps baited with aged chicken. We created 41 independent genetic lines from wild-caught pairs by providing a 40g mouse carcass for each pair and allowing them to breed. We designated the offspring from the wild-caught pairs as the first parental generation. After eclosion and emergence of this first laboratory-bred generation, we placed individuals in small plastic containers (15.6 x 11.6 x 6.7 cm), fed them ad libitum raw chicken liver twice weekly, and maintained them on a 14:10 h light:dark cycle at 21°C until they were used in experiments. We designated the date of eclosion as the first day of life for all beetles used in the experiments.

Experimental design

The purpose of this experiment was to determine the effect on lifetime fitness of potential multigenerational effects of parental body size and natal carcass size in N. marginatus. We measured three fitness response variables: lifespan, total number of offspring, and number of offspring produced in the first brood. Number of offspring in the first brood was used in addition to lifetime number of offspring because number in the first brood may or may not follow total lifetime numbers [39], and in the natural environment, number of reproductive bouts may be fewer than that observed in laboratory experiments. Thus, number in the first brood may represent natural conditions better than total lifetime number of offspring in a laboratory environment. To generate potential multigenerational effects from parental body size and natal carcass size, we allowed large and small beetles to reproduce on large or small carcasses (first parental generation). To assess fitness effects of multigenerational effects, we then allowed female offspring from this first parental generation to reproduce throughout their lifetime. We then measured the three fitness responses for all females of this second generation and compared them among treatment combinations.

To determine what sizes constituted large or small beetles for assignment in the first parental generation, we used the distribution of pronotum widths from wild-caught beetles. We assigned beetles from the first parental generation with pronotum widths > 1 standard deviation above and < 1 standard deviation below the mean (derived from wild-caught population) as large and small, respectively. In the wild-caught population, the mean pronotum width of females was 6.67mm, with a standard deviation of 0.78mm (N = 50). The mean pronotum width of males was 6.87mm, with a standard deviation of 0.72mm (N = 50). Thus, the size range of large and small female beetles that we used in this experiment for the first parental generation was 7.44mm– 8.22mm and 5.11mm– 5.89mm, respectively, and the corresponding size range for large and small males was 7.60mm– 8.32mm and 5.42mm– 6.15mm, respectively. For this first part of the experiment, we used a fully crossed factorial design. There were four parental size treatments—large male with large female, large male with small female, small male with large female, and small male with small female. Each parental size treatment was crossed with both small (20g) and large (40g) carcass sizes, for a total of eight treatment combinations. We chose 20g and 40g carcass sizes based on a previous study that tested multiple carcass sizes from 5g to 50 g. The 20g and 40g sizes were both within the range of carcass sizes whereon N. marginatus experienced equally high reproductive success [69]. We completed six replicates of each of the eight treatment combinations resulting in an initial sample size of 48 pairs for the first parental generation.

We began each first-generation experimental replicate by randomly choosing a genetically unrelated pair of beetles that fit into one of the parental size treatments. We placed the pair in a small brood container and randomly assigned them either a 20g (± 1.0g) or a 40g (± 2.0g) mouse carcass. We checked the brood containers daily for larvae, and after larvae arrived on the carcass, we removed the lid of the small brood container and placed the small container in an abandonment chamber (see [70] for details). We checked abandonment chambers daily for leaving adults or dispersal of larvae, and when the carcass was consumed and larvae dispersed into the soil, we removed and weighed the remaining parent(s). The larvae from each brood reached eclosion 4–5 weeks after dispersal. We weighed each newly-eclosed adult offspring, placed them in an individual container, and fed them ad libitum chicken liver until they reached sexual maturity. We used results from this first-generation experiment to test for effects of body size of parents (male and female separately) and carcass size on reproductive output and offspring traits [65]. In the first-generation experiment female body size generated significant effects on offspring body size, but male size had no effect on offspring traits and there were no significant interactions between male and female body size [65]. For this reason, we included parental size treatments as four independent treatments in analysis of the second-generation experiment (this paper) rather than as a factorial. This reduced complexity of the second-generation analysis by eliminating some two-way and three-way, and all four-way interactions. For additional information on the first parental generation methods and results from the experiment, see Smith and Belk [65].

For the second parental generation, we used the offspring from the first parental experiment described above to determine how the size of parental N. marginatus beetles and the size of carcass that they reproduced on affected lifetime fitness of their offspring. For the second parental generation, we randomly chose two female offspring from each of the first parental replicates for the experiment. These two females (from replicates of the eight first generation treatment combinations) were randomly assigned either large (40g) or small (20g) carcasses for reproduction, for a total of sixteen treatment combinations in the second experiment. We started six replicates for each of the sixteen treatments for a total of 96 replicates. Five experimental pairs failed to reproduce (one each for five of the treatment combinations), so the realized sample size was 91 pairs.

To determine fitness of second-generation beetles, sexually mature females (age > 21 days) were paired with a randomly selected, sexually mature, genetically unrelated male, and the pair was placed in a plastic container (14 × 13 × 17cm) filled with 10cm of moist soil and given either a 20g (±1.0g) or a 40g (± 2.0g) mouse carcass (based on the random assignment described above). The containers were kept in an environmental chamber at 21°C on a 14:10 h light:dark cycle. We checked for larvae daily, and after larvae arrived on the carcass, we removed the male from the container so that only the female cared for the offspring. After the larvae dispersed into the soil to pupate, we removed the female and placed her in a small container with ad libitum chicken liver for two days, and then set her up to mate again with a new, randomly selected, genetically unrelated, virgin male on the same size carcass (20g or 40g). This cycle continued for her entire life. In the second-generation experiment, number of successful reproductive bouts ranged from 1 to 5 with a mean of 2.9 bouts. We measured lifespan as the number of days the female survived after eclosion. After the offspring from each brood of this second-generation experiment enclosed as adults, we recorded the sex, weight, and pronotum width for each beetle. We summed the number of offspring from each brood to determine a female’s lifetime number of offspring.

Analysis

To determine if parental size or natal carcass size influences fitness of offspring we used a mixed model analysis of covariance (ANCOVA) approach (SAS, Proc MIXED). We used three response variables to represent fitness of females from the second parental generation: i.e., total lifetime number of offspring, total number of offspring in the first brood, and lifespan. Predictor variables for each of the three models were first parental generation body size (four levels), natal carcass size (two levels), current carcass size (two levels), and pronotum size of second parental generation focal female (covariate). Initially we included all two-way and the three-way interactions of main effects in the model. However, interaction terms were not significant in any of the models, so, we report results from a reduced model that included only one, two-way interaction–natal carcass size by current carcass size. This interaction was of interest because of the significant effect of current carcass size on fitness measures, and the possibility of a multigenerational effect that natal carcass size might provide some “priming” for efficiency of use of a similar carcass size. Because we used two individuals from each of the first-generation broods to breed for the second generation, we used first generation parental brood ID as a random effect to account for the relatedness of individuals from the same brood. We used raw data for the analysis, and inspection of residual plots showed no departure from assumptions for the parametric model.

Results

None of our three measures of fitness were significantly related to parental body size (first generation parents) or natal carcass size. Current carcass size was a significant predictor for lifetime number of offspring, and number of offspring in the first brood. Pronotum width of the female was a significant predictor of life span of the female (Table 1). On average lifetime number of offspring was about 20% less on small carcasses compared to large carcasses; and the number of offspring in the first brood was about 28% less on small carcasses compared to large carcasses (Table 2). The largest females (7.7 mm pronotum width) lived up to 19 days longer than the smallest females (5 mm pronotum width), but this increased lifespan had no effect on lifetime number of offspring (Table 1).

Table 1. Results of mixed model analysis of covariance for three fitness measures for N. marginatus.

Dependent Variable	Effect	Num df/Den df	F-Value	p-value
Lifetime Number of Offspring	Parental Size	3/35.7	0.25	0.8637
	Natal Carcass Size	1/35	0.33	0.5676
	Carcass Size	1/48.8	6.26	0.0158
	Pronotum	1/82.4	2.49	0.1185
	Natal Carcass Size*Carcass Size	1/48.4	0.04	0.8455
Lifespan of Female	Parental Size	3/39.2	0.77	0.5190
	Natal Carcass Size	1/38.4	1.08	0.3056
	Carcass Size	1/53.3	0.04	0.8483
	Pronotum	1/81.8	9.92	0.0023
	Natal Carcass Size*Carcass Size	1/52.8	1.45	0.2343
Number of Offspring from First Bout	Parental Size	3/27.4	1.65	0.2011
	Natal Carcass Size	1/26.7	0.45	0.5082
	Carcass Size	1/44	13.36	0.0007
	Pronotum	1/77.6	3.41	0.0687
	Natal Carcass Size*Carcass Size	1/43.5	0.01	0.9385

Open in a new tab

Table 2. Least squares means and upper and lower confidence intervals for main effects of current carcass size and the interaction between current carcass size and natal carcass size in N. marginatus.

Effect	Mean	Lower CI (95%)	Upper CI (95%)
Lifetime Number of Offspring
Carcass (20 g)	40.74	34.69	46.79
Carcass (40 g)	50.79	44.72	56.86
Natal Carcass (20 g)*Carcass (20 g)	39.02	30.20	47.85
Natal Carcass (20 g)*Carcass (40 g)	49.86	41.69	58.03
Natal Carcass (40 g)*Carcass (20 g)	42.45	34.17	50.73
Natal Carcass (40 g)*Carcass (40 g)	51.72	42.75	60.68
Lifespan of Female (days)
Carcass (20 g)	60.89	57.38	64.40
Carcass (40 g)	60.43	56.90	63.96
Natal Carcass (20 g)*Carcass (20 g)	60.83	55.71	65.95
Natal Carcass (20 g)*Carcass (40 g)	63.22	58.46	67.98
Natal Carcass (40 g)*Carcass (20 g)	60.95	56.12	65.77
Natal Carcass (40 g)*Carcass (40 g)	57.64	52.44	62.85
Number of Offspring from First Bout
Carcass (20 g)	14.03	11.94	16.13
Carcass (40 g)	19.36	17.26	21.46
Natal Carcass (20 g)*Carcass (20 g)	13.46	10.40	16.53
Natal Carcass (20 g)*Carcass (40 g)	18.90	16.07	21.73
Natal Carcass (40 g)*Carcass (20 g)	14.60	11.73	17.47
Natal Carcass (40 g)*Carcass (40 g)	19.81	16.70	22.93

Open in a new tab

Discussion

Multigenerational effects have been widely studied and reported, especially in invertebrates [3, 5–8]. Despite ample evidence of multigenerational effects, their relationship with offspring fitness is not well established. In N. marginatus burying beetles, we previously documented two mechanisms that resulted in multigenerational effects on offspring body size–larger females produced larger offspring, and larger reproductive carcasses resulted in larger offspring [65]. However, larger body size in response to larger natal carcass size or larger parent size did not result in increased fitness measured as lifetime number of offspring. In many other species, body size is considered a strong predictor of fitness, and body size variation through maternal effects can lead to large differences in individual fitness [23–25]. Why do multigenerational effects of increased body size have no effect on lifetime fitness in N. marginatus? The strongest determinant of fitness in our study was size of carcass available for reproduction. Females, of any size, producing offspring on larger carcasses, produced more offspring over a lifetime than those producing offspring on smaller carcasses. These results contrast with those from N. vespilloides where larger females had a reproductive advantage (i.e., produced more offspring) on larger carcasses and smaller females had an advantage on smaller carcasses [71]. This difference observed between our study and that of Hopwood et al. [71] may be a reflection of differences in individual ecology between species [65]. Additional studies of the relationship between body size and carcass size and the consequences for reproductive output and lifetime fitness (e.g., [69, 72]) would help to determine the generality of our results.

Another interesting point from our data is that lifespan was not influenced by size of carcass used for reproduction, but lifetime number of offspring was significantly influenced by carcass size. Although we would expect some relationship between fitness and lifespan in general, across the range of lifespans observed in this experiment there was no relationship. In a study on the burying beetle N. orbicollis, carcass size significantly influenced lifespan, but fitness (measured as lifetime number of offspring) did not differ between larger and smaller carcasses [72]. This was interpreted as different reproductive strategies resulting in equal fitness–females reproducing on larger carcasses produced more offspring in each reproductive bout, but had shorter lifespans and thus fewer reproductive bouts; whereas, females reproducing on smaller carcasses produced fewer offspring per reproductive bout, but had longer lifespans and more reproductive bouts [72]. Our results are not consistent with this pattern or interpretation, but rather suggest that in N. marginatus larger carcasses produce greater lifetime number of offspring compared to smaller carcasses. This difference between studies may reflect variation in the relationship between carcass size and fitness between species of burying beetles. Generally, optimal carcass size scales with body size in burying beetles; however, relationships between carcass size and fitness are not well known in most species of burying beetles. Variation in the efficiency of use of various carcass sizes has been documented among a few species [69, 72]. Additional studies that compare lifetime reproductive output on various carcass sizes would help determine general patterns of variation in reproductive strategies among species and carcass sizes.

Multigenerational effects in burying beetles (genus: Nicrophorus) are well established [11, 33, 52, 65–68]. Most of these studies investigate the relationship between maternal size and offspring size [11, 33, 52, 65, 66, 73]. However, none of these studies investigated whether size related multigenerational effects affect offspring lifetime fitness. Two studies investigated the relationship between multigenerational effects and offspring survival but did not study their role in lifetime fitness of offspring [66, 68], and our data suggest that longer lifespan does not necessarily contribute to increased number of offspring over a lifetime (i.e., fitness). In natural environments, number of successful reproductive bouts may be fewer than that in our non-competitive lab environment. For this reason, we included number of offspring in the first bout as a potentially more natural alternative to measure lifetime reproductive success. Patterns were the same whether we measured fitness as lifetime number of offspring or number of offspring in the first bout, suggesting that even if females reproduce on only one carcass during their lifetime, there is still no effect of parental body size or natal carcass size.

The lack of a multigenerational effect of body size on offspring fitness that we found in this study may be due to the absence of competition in the lab environment. In our experiment, we allowed female offspring in the second generation to reproduce regardless of their size, which might not happen in nature. Burying beetles compete for access to carcasses, and generally, the largest male and female beetles dominate the carcass for reproduction [57, 60, 65]. In our study, the only factor that affected fitness was the size of the carcass on which the female reproduced, with more offspring produced on larger carcasses (Table 1). Other studies have shown that larger females have larger offspring [65, 73], which could confer a fitness advantage of large size through a maternal effect under more natural conditions where size determines whether or not a female wins access to a carcass and how many carcasses she dominates. Thus, large body size of a female beetle may translate into increased lifetime fitness in her offspring in a natural environment because larger female offspring are able to win access to more and larger carcasses, and thus produce more offspring.

We acknowledge that competitive ability linked to individual body size may confer a fitness advantage under some circumstances, especially if access to carcasses for reproduction is frequently contested, and if body size is often linked to success in obtaining control of carcasses. However, at least three lines of evidence suggest that competition for carcasses may not be a consistent determinant of lifetime fitness. First, competition for carcasses is dependent on the density of beetles and the availability of small vertebrate carcasses at both large and small scales. Densities of beetles and small vertebrate carcasses fluctuate dramatically among years [74, 75]. Similarly, when we trap beetles from the wild for this and other studies, we find variation in the number of beetles captured in a given trap, and a range of sizes of both males and females. This spatial variation in number and body size and the temporal variation in beetle numbers and carcass numbers among and within years suggests that competition for carcasses is likely a local phenomenon. All beetles in a given area are not present and competing for every carcass. Although large beetles may win at carcasses where they compete, some carcasses will have many competitors, and some will have few. Also, when beetles breed on a carcass, they are effectively removed from the potentially competing population for at least two weeks. Thus, the competitive environment is best represented by a mosaic of local carcass availability and local beetle distribution and availability. The outcome is a range of opportunities for beetles of many sizes to be successful at finding and breeding on a carcass. Second, burying beetles exhibit alternative reproductive strategies such that fitness can be obtained by males and females acting as satellites at the carcass burial site or mating prior to finding a carcass [76–78]. If only large individuals can gain access to and reproduce successfully on carcasses, then alternative strategies would not evolve, and body size would be more strongly constrained by selection. Alternative reproductive strategies and a range of body sizes in natural populations suggest that being large is not the only way to be successful in competition for carcasses. Third, in a previous study, we measured competitive ability to gain a carcass based on size in both male and female burying beetles [65]. The relationship differed by sex such that for females, the size difference between competitors had to be much larger for body size to be an important determinant of competitive outcomes. Even for males, there was some non-zero probability of the smaller competitor winning the carcass, except at the largest size difference [65]. Other studies on burying beetles have reported corroborating effects of beetle sizes found on carcasses in natural systems [33]. Body size may be a strong determinant of success in competing for carcasses, but in many contests, priority effects and stochasticity or “luck” may be equally or more important. Although competition for carcasses provides a plausible mechanism for generating fitness effects from multigenerational effects, we urge caution in suggesting that this is a strong and pervasive effect. We simply do not know enough about the frequency and intensity of competition for carcasses in natural systems to be confident in asserting the relative importance of body size.

In addition to dominance in competitive environments, larger body size also confers increased resistance to starvation [65]. Resistance to starvation could be important to lifetime fitness in environments where food resources are limited. However, burying beetles can feed on many forms of carrion that are otherwise unsuitable for reproduction, and we know almost nothing about the relative abundance of carcasses for feeding in burying beetle communities, and the corresponding threat of starvation for adult burying beetles. Thus, similar to the argument for the potential selective importance of body size to competition for carcasses, limited resources and the possibility of starvation is likely to be experienced only episodically in burying beetle populations.

In summary, the lack of relationship between multigenerational effects on body size and offspring lifetime fitness suggests that these maternal effects are best understood as “selfish maternal effects” sensu [4]. Females appear to be maximizing their own fitness even though that may have no effect on individual offspring lifetime fitness. If, on the other hand, females were using cues from their current environment (such as a large carcass with no competition, or a small carcass with many competitors) in an anticipatory way to determine offspring body size [4], then we might expect natal carcass size to have an effect on lifetime fitness in a similar environment. In our experiment, this should have resulted in a significant two-way interaction between natal carcass size and current carcass size. However, this interaction term was not significant in any of our three measures of lifetime fitness. We reiterate the caution from Marshall and Uller [4] that fitness of offspring resulting from multigenerational effects should not be assumed based on phenotypic traits of offspring, but should be based on experiments that measure lifetime fitness of offspring.

Acknowledgments

We thank the Charles Redd Center and the Biology Department at Brigham Young University for graduate support for Ashlee Momcilovitch. We thank the numerous Belk Laboratory undergraduate research assistants from 2014 to 2015 for their contributions to maintenance of the beetles in this experiment.

Data Availability

All the data used in this study are available from the Dryad database (DOI: https://doi.org/10.5061/dryad.1vhhmgqt0).

Funding Statement

The authors received no specific funding for this work.

References

1.Rutledge JJ, Robison OW, Eisen EJ, Legates JE. Dynamics of genetic and maternal effects in mice. J Anim Sci. 1972; 35(5): 911–8. doi: 10.2527/jas1972.355911x [DOI] [PubMed] [Google Scholar]
2.Lande R, Kirkpatrick M. Selection response in traits with maternal inheritance. Genet Res. 1990; 55(3): 189–97. doi: 10.1017/s0016672300025520 [DOI] [PubMed] [Google Scholar]
3.Rossiter MC. Incidence and consequences of inherited environmental effects. Annu Rev Ecol Syst. 1996; 27: 451–76. [Google Scholar]
4.Marshall DJ, Uller T. When is a maternal effect adaptive? Oikos. 2007; 116: 1957–63. [Google Scholar]
5.Bernardo J. Maternal effects in animal ecology. Am Zool. 1996; 36(2): 83–105. [Google Scholar]
6.Fox C, Mousseau T. Maternal effects as adaptations for transgenerational phenotypic plasticity in insects. In: Maternal Effects as Adaptions. 1998. p. 159–77. [Google Scholar]
7.Bicho RC, Santos FCF, Scott-Fordsmand JJ, Amorim MJB. Multigenerational effects of copper nanomaterials (cuonms) are different of those of cucl2: exposure in the soil invertebrate Enchytraeus crypticus. Sci Rep. 2017; 7(1): 1–7. doi: 10.1038/s41598-016-0028-x [DOI] [PMC free article] [PubMed] [Google Scholar]
8.Schür C, Zipp S, Thalau T, Wagner M. Microplastics but not natural particles induce multigenerational effects in Daphnia magna. Environ Pollut. 2020; 260: 113904. doi: 10.1016/j.envpol.2019.113904 [DOI] [PubMed] [Google Scholar]
9.Fox CW, Thakar MS, Mousseau TA. Egg size plasticity in a seed beetle: an adaptive maternal effect. Am Nat. 1997; 149(1): 149–63. [Google Scholar]
10.Boots M, Roberts KE. Maternal effects in disease resistance: poor maternal environment increases offspring resistance to an insect virus. Proc R Soc B Biol Sci. 2012; 279(1744): 4009–14. [DOI] [PMC free article] [PubMed] [Google Scholar]
11.Steiger S. Bigger mothers are better mothers: disentangling size-related prenatal and postnatal maternal effects. Proc R Soc B Biol Sci. 2013; 280(1766): 20131225. doi: 10.1098/rspb.2013.1225 [DOI] [PMC free article] [PubMed] [Google Scholar]
12.Bloch Qazi MC, Miller PB, Poeschel PM, Phan MH, Thayer JL, Medrano CL. Transgenerational effects of maternal and grandmaternal age on offspring viability and performance in Drosophila melanogaster. J Insect Physiol. 2017; 100: 43–52. doi: 10.1016/j.jinsphys.2017.05.007 [DOI] [PubMed] [Google Scholar]
13.Vinogradova EB, Reznik SY. Influence of a single (stepwise) change in photoperiod and female age on larval diapause in the blowfly. Entomol Rev. 2002; 82(9): 1190–6. [Google Scholar]
14.Prasad NG, Shakarad M, Rajamani M, Joshi A. Interaction between the effects of maternal and larval levels of nutrition on pre-adult survival in Drosophila melanogaster. Evol Ecol Res. 2003; 5(6): 903–11. [Google Scholar]
15.Opit GP, Throne JE. Influence of maternal age on the fitness of progeny in the rice weevil, Sitophilus oryzae (coleoptera: curculionidae). Environ Entomol. 2007; 36(1): 83–9. doi: 10.1603/0046-225x(2007)36[83:iomaot]2.0.co;2 [DOI] [PubMed] [Google Scholar]
16.Singh K, Omkar. Effect of parental ageing on offspring developmental and survival attributes in an aphidophagous ladybird, Cheilomenes sexmaculata. J Appl Entomol. 2009; 133(7): 500–4. [Google Scholar]
17.Smallegange IM. Effects of paternal phenotype and environmental variability on age and size at maturity in a male dimorphic mite. Naturwissenschaften. 2011; 98(4): 339–46. doi: 10.1007/s00114-011-0773-4 [DOI] [PubMed] [Google Scholar]
18.Ducatez S, Baguette M, Stevens VM, Legrand D, Fréville H. Complex interactions between paternal and maternal effects: parental experience and age at reproduction affect fecundity and offspring performance in a butterfly. Evolution. 2012; 66(11): 3558–69. doi: 10.1111/j.1558-5646.2012.01704.x [DOI] [PubMed] [Google Scholar]
19.Mestre L, Bonte D. Food stress during juvenile and maternal development shapes natal and breeding dispersal in a spider. Behav Ecol. 2012; 23(4): 759–64. [Google Scholar]
20.Vargas G, Michaud JP, Nechols JR. Maternal effects shape dynamic trajectories of reproductive allocation in the ladybird Coleomegilla maculata. Bull Entomol Res. 2012; 102(5): 558–65. doi: 10.1017/S000748531200020X [DOI] [PubMed] [Google Scholar]
21.Pick JL, Ebneter C, Hutter P, Tschirren B. Disentangling genetic and prenatal maternal effects on offspring size and survival. Am Nat. 2016; 188(6): 628–39. doi: 10.1086/688918 [DOI] [PubMed] [Google Scholar]
22.Bock MJ, Jarvis GC, Corey EL, Stone EE, Gribble KE. Maternal age alters offspring lifespan, fitness, and lifespan extension under caloric restriction. Sci Rep. 2019; 9(1): 1–16. doi: 10.1038/s41598-018-37186-2 [DOI] [PMC free article] [PubMed] [Google Scholar]
23.Pierotti R, Clutton-Brock TH. Reproductive success: studies of individual variation in contrasting breeding systems. Condor. 1989; 91(3): 750. [Google Scholar]
24.Shine R, Reiss MJ. The allometry of growth and reproduction. J Anim Ecol. 1990; 59(3): 1197. [Google Scholar]
25.Waller JT, Svensson EI. Body size evolution in an old insect order: no evidence for cope’s rule in spite of fitness benefits of large size. Evolution. 2017; 71(9): 2178–93. doi: 10.1111/evo.13302 [DOI] [PubMed] [Google Scholar]
26.Berger A. Egg weight, batch size and fecundity of the spotted stalk borer, Chilo partellus in relation to weight of females and time of oviposition. Entomol Exp Appl. 1989; 50(3): 199–207. [Google Scholar]
27.Kim JY. Female size and fitness in the leaf-cutter bee Megachile apicalis. Ecol Entomol. 1997; 22(3): 275–82. [Google Scholar]
28.Fox CW, Savalli UM. Inheritance of environmental variation in body size: superparasitism of seeds affects progeny and grandprogeny body size via a nongenetic maternal effect. Evolution. 1998; 52: 172–82. doi: 10.1111/j.1558-5646.1998.tb05150.x [DOI] [PubMed] [Google Scholar]
29.Wainhouse D, Ashburner R, Boswell R. Reproductive development and maternal effects in the pine weevil Hylobius abietis. Ecological Entomology. 2001; 26: 655–61. [Google Scholar]
30.Fischer K, Zwaan BJ, Brakefield PM. How does egg size relate to body size in butterflies? Oecologia. 2002; 131(3): 375–9. doi: 10.1007/s00442-002-0913-9 [DOI] [PubMed] [Google Scholar]
31.Vargas G, Michaud JP, Nechols JR. Cryptic maternal effects in Hippodamia convergens vary with maternal age and body size. Entomol Exp Appl. 2013; 146(2): 302–11. [Google Scholar]
32.Kojima W. Variation in body size in the giant rhinoceros beetle Trypoxylus dichotomus is mediated by maternal effects on egg size. Ecol Entomol. 2015; 40(4): 420–7. [Google Scholar]
33.Scott MP, Traniello JFA. Behavioural and ecological correlates of male and female parental care and reproductive success in burying beetles (Nicrophorus spp.). Anim Behav. 1990; 39(2): 274–83. [Google Scholar]
34.Barneche DR, Burgess SC, Marshall DJ. Global environmental drivers of marine fish egg size. Glob Ecol Biogeogr. 2018; 27(8): 890–8. [Google Scholar]
35.Bartlett J, Ashworth CM. Brood size and fitness in Nicrophorus vespilloides (coleoptera: Silphidae). Behav Ecol Sociobiol. 1988; 22(6): 429–34. [Google Scholar]
36.Sieber DJ, Paquet M, Smiseth PT. Joint effects of brood size and resource availability on sibling competition. Anim Behav. 2017; 129: 25–30. [Google Scholar]
37.Kawecki TJ. Adaptive plasticity of egg size in response to competition in the cowpea weevil, Callosobruchus maculatus (coleoptera: Bruchidae). Oecologia. 1995; 102(1): 81–5. doi: 10.1007/BF00333313 [DOI] [PubMed] [Google Scholar]
38.Visser ME. The influence of competition between foragers on clutch size decisions in an insect parasitoid with scramble larval competition. Behav Ecol. 1996; 7(1): 109–14. [Google Scholar]
39.Creighton JC. Population density, body size, and phenotypic plasticity of brood size in a burying beetle. Behav Ecol. 2005; 16(6): 1031–6. [Google Scholar]
40.Woelber BK, Hall CL, Howard DR. Environmental cues influence parental brood structure decisions in the burying beetle Nicrophorus marginatus. J Ethol. 2018; 36(1): 55–64. [Google Scholar]
41.McGregor PK, Krebs JR, Perrins CM. Song repertoires and lifetime reproductive success in the great tit (Parus major). Am Nat. 1981; 118(2): 149–59. [Google Scholar]
42.MacColl ADC, Hatchwell BJ. Determinants of lifetime fitness in a cooperative breeder, the long-tailed tit Aegithalos caudatus. J Anim Ecol. 2004; 73(6): 1137–48. [Google Scholar]
43.Felsenstein J, Lewontin RC. The genetic basis of evolutionary change. Evolution. 1975; 29(3): 587. [Google Scholar]
44.Allendorf FW, Leary RF. Heterozygosity and fitness in natural populations of animals. Conserv Biol Sci Scarcity Divers. 1986; 57: 58–72. [Google Scholar]
45.Gilbert NE, Endler JA. Natural selection in the wild. J Anim Ecol. 1987; 56(2): 719. [Google Scholar]
46.Wang S, Hard JJ, Utter F. Genetic variation and fitness in salmonids. Conserv Genet. 2002; 3: 321–33. [Google Scholar]
47.Jervis MA, Ferns PN. The timing of egg maturation in insects: ovigeny index and initial egg load as measures of fitness and of resource allocation. Oikos. 2004. 107; 449–61. [Google Scholar]
48.South A, Lewis SM. The influence of male ejaculate quantity on female fitness: a meta-analysis. Biol Rev. 2011; 86(2): 299–309. doi: 10.1111/j.1469-185X.2010.00145.x [DOI] [PubMed] [Google Scholar]
49.Kant R, Minor MA, Trewick SA, Sandanayaka WRM. Body size and fitness relation in male and female Diaeretiella rapae. BioControl. 2012; 57(6): 759–66. [Google Scholar]
50.Langley PA, Pimley RW, Mews AR, Flood MET. Effect of diet composition on feeding, digestion, and reproduction in Glossina morsitans. J Insect Physiol. 1978; 24(3): 233–8. [Google Scholar]
51.Gustafsson S, Rengefors K, Hansson LA. Increased consumer fitness following transfer of toxin tolerance to offspring via maternal effects. Ecology. 2005; 86(10): 2561–7. [Google Scholar]
52.Paquet M, Smiseth PT. Females manipulate behavior of caring males via prenatal maternal effects. Proc Natl Acad Sci U S A. 2017; 114(26): 6800–5. doi: 10.1073/pnas.1619759114 [DOI] [PMC free article] [PubMed] [Google Scholar]
53.Coakley CM, Nestoros E, Little TJ. Testing hypotheses for maternal effects in Daphnia magna. J Evol Biol. 2018; 31(2): 211–6. doi: 10.1111/jeb.13206 [DOI] [PMC free article] [PubMed] [Google Scholar]
54.Fetherston IA, Scott MP, Traniello JFA. Parental care in burying beetles: the organization of male and female brood‐care behavior. Ethology. 1990; 85(3): 177–90. [Google Scholar]
55.Rauter CM, Moore AJ. Do honest signalling models of offspring solicitation apply to insects? Proc R Soc B Biol Sci. 1999; 266(1429): 1691–6. [Google Scholar]
56.Trumbo ST. Infanticide, sexual selection and task specialization in a biparental burying beetle. Anim Behav. 2006; 72(5): 1159–67. [Google Scholar]
57.Otronen M. The effect of body size on the outcome of fights in burying beetles (Nicrophorus). Ann Zool Fennici. 1988; 25(2): 191–201. [Google Scholar]
58.Scott MP. Brood guarding and the evolution of male parental care in burying beetles. Behav Ecol Sociobiol. 1990; 26(1): 31–9. [Google Scholar]
59.Scott MP. The benefit of paternal assistance in intra- and interspecific competition for the burying beetle, Nicrophorus defodiens. Ethol Ecol Evol. 1994; 6(4): 537–43. [Google Scholar]
60.Eggert AK, Sakaluk SK. Benefits of communal breeding in burying beetles: a field experiment. Ecol Entomol. 2000; 25(3): 262–6. [Google Scholar]
61.Müller JK, Eggert AK, Dressel J. Intraspecific brood parasitism in the burying beetle, Nicrophorus vespilloides (coleoptera: Silphidae). Anim Behav. 1990; 40(3): 491–9. [Google Scholar]
62.Safryn SA, Scott MP. Sizing up the competition: do burying beetles weigh or measure their opponents? J Insect Behav. 2000; 13(2): 291–7. [Google Scholar]
63.Hopwood PE, Moore AJ, Royle NJ. Nutrition during sexual maturation affects competitive ability but not reproductive productivity in burying beetles. Funct Ecol. 2013; 27(6): 1350–7. [Google Scholar]
64.Lee VE, Head ML, Carter MJ, Royle NJ. Effects of age and experience on contest behavior in the burying beetle, Nicrophorus vespilloides. Behav Ecol. 2014; 25(1): 172–9. doi: 10.1093/beheco/art101 [DOI] [PMC free article] [PubMed] [Google Scholar]
65.Smith AN, Belk MC. Does body size affect fitness the same way in males and females? a test of multiple fitness components. Biol J Linn Soc. 2018; 124(1): 47–55. [Google Scholar]
66.Lock JE, Smiseth PT, Moore PJ, Moore AJ. Coadaptation of prenatal and postnatal maternal effects. Am Nat. 2007; 170(5): 709–18. doi: 10.1086/521963 [DOI] [PubMed] [Google Scholar]
67.Paquet M, Parenteau C, Ford LE, Ratz T, Richardson J, Angelier F, et al. Females adjust maternal hormone concentration in eggs according to male condition in a burying beetle. Horm Behav. 2020; 121: 104708. doi: 10.1016/j.yhbeh.2020.104708 [DOI] [PubMed] [Google Scholar]
68.Richardson J, Ross J, Smiseth PT. Food deprivation affects egg laying and maternal care but not offspring performance in a beetle. Behav Ecol. 2019; 30(5): 1477–87. [Google Scholar]
69.Meyers PJ. Variation in resource utilization and cost of reproduction for two burying beetle species [Master’s Thesis]. Provo (UT): Brigham Young University; 2014.
70.Smith AN, Belk MC, Creighton JC. Residency time as an indicator of reproductive restraint in male burying beetles. PLoS One. 2014; 9(10): 109165 doi: 10.1371/journal.pone.0109165 [DOI] [PMC free article] [PubMed] [Google Scholar]
71.Hopwood PE, Moore AJ, Tregenza T, Royle NJ. Niche variation and the maintenance of variation in body size in a burying beetle. Ecol Entomol. 2016; 41(1): 96–104. [Google Scholar]
72.Creighton JC, Heflin ND, Belk MC. Cost of reproduction, resource quality, and terminal investment in a burying beetle. Am Nat. 2009; 174(5): 673–84. doi: 10.1086/605963 [DOI] [PubMed] [Google Scholar]
73.Rauter CM, McGuire MJ, Gwartney MM, Space JE. Effect of population density and female body size on number and size of offspring in a species with size-dependent contests over resources. Ethology. 2010; 116(2): 120–8. [Google Scholar]
74.Scott MP. The ecology and behavior of burying beetles. Annu Rev of Entomol. 1998; 43: 595–618. doi: 10.1146/annurev.ento.43.1.595 [DOI] [PubMed] [Google Scholar]
75.Smith RJ, Hines A, Richmond S, Merrick M, Drew A, Fargo R. Altitudinal variation in body size and population density of Nicrophorus investigator (coleoptera: Silphidae). Environ Entomol. 2000; 29(2): 290–8. [Google Scholar]
76.Eggert AK. Alternative male mate-finding tactics in burying beetles. Behav Ecol. 1992; 3(3): 243–54. [Google Scholar]
77.Müller JK, Eggert AK. Paternity assurance by “helpful” males: adaptations to sperm competition in burying beetles. Behav Ecol Sociobiol. 1989; 24(4): 245–9. [Google Scholar]
78.Müller JK, Braunisch V, Hwang W, Eggert AK. Alternative tactics and individual reproductive success in natural associations of the burying beetle, Nicrophorus vespilloides. Behav Ecol. 2007; 18(1): 196–203. [Google Scholar]

PLoS One. doi: 10.1371/journal.pone.0253885.r001

Decision Letter 0

William David Halliday

23 Apr 2021

PONE-D-21-10116

No evidence for increased fitness from multigenerational effects of parental size or natal resource quality in the burying beetle Nicrophorus marginatus

PLOS ONE

Dear Dr. Belk,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

This manuscript has been assessed by two reviewers who both felt it had a lot of strengths, but also have a number of comments that require further clarification. Please address all of these comments when revising your manuscript.

Please submit your revised manuscript by Jun 07 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols.

We look forward to receiving your revised manuscript.

Kind regards,

William David Halliday, Ph.D.

Academic Editor

PLOS ONE

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

In your Methods section, please provide additional information regarding the permits you obtained for the work. Please ensure you have included the full name of the authority that approved the field site access and, if no permits were required, a brief statement explaining why.

We note that you have stated that you will provide repository information for your data at acceptance. Should your manuscript be accepted for publication, we will hold it until you provide the relevant accession numbers or DOIs necessary to access your data. If you wish to make changes to your Data Availability statement, please describe these changes in your cover letter and we will update your Data Availability statement to reflect the information you provide.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The manuscript tests whether variation in two aspects of the parental environment, i.e. parental body size and size of breeding resources, affects offspring fitness. The results suggest that there are no such multigenerational effects. The authors employ a sound experimental manipulation and carefully interpret the results in this very well written manuscript. My main comment is to develop the rationale for the study (see my comment below). When I first read the methods, I was also concerned that the sample size may be too small to have confidence that null results are likely truly null (91 data points across 16 treatment groups). However, the authors found statistically significant effects elsewhere with the same sample size. If trans-generational effects are expected to be of a similar magnitude, there should have been enough power to detect them. Other than that, I only have minor suggestions.

A point that I think is important to emphasise throughout the paper is why and when (adaptive) multigenerational effects are expected to evolve in this system. Burying beetles experience a lot of variation in the size of the carcasses they encounter in the wild. Body size also varies a lot between generations because it is contingent on sibling competition and resource acquisition during larval development. Given so little reliability of the future environment for offspring, it seems unlikely that anticipatory effects could evolve. And, if they exist, these effects might be very small relative to effects of the current environment, such as size of the current carcass. Any such multigenerational effects could thus be masked by the influence of current environment. In other words, it is not clear to me why we should expect to see multigenerational effects in burying beetles. I suggest that you make a stronger case and clarifying the arguments for why this species provides a good system to investigate multigenerational effects.

In some places the authors use "resource quality" to refer to "carcass size", which can be confused with other aspects of the resource (e.g. nutritional value, freshness). This confusion can be avoided by using "amount of resources", or simply "carcass size" or "carcass mass" in place of "quality".

In the abstract, you point out that there was no evidence for increased fitness as a result of multigenerational effects (line 32). Given that these effects could be in both directions, increasing or decreasing fitness, I suggest rephrasing to make the sentence more general. For example, you could say that there was no evidence that multigenerational effects contributed to fitness or, to be more explicit about directionality, that there was no evidence for increased fitness resulting from multigenerational effects in favourable natal environments.

The introduction provides a clear account of the topic and introduces the study system very well. My only comment would be to add predictions regarding the direction of the multigenerational effects. Some of these predictions are already provided in the last paragraph of the discussion. It would be useful to have them earlier on so that the reader is better prepared to assess the methods and results. This could also help motivating the study and provide reasons as to why we should expect multigenerational effects on fitness in burying beetles. Is it because carcass size in previous generations would be a reliable cue for carcass size or the intensity of competition in current generation?

In lines 80-81, do you consider effects of the current carcass as multigenerational effects? This is not necessarily intuitive given that the size of the carcass can impact directly on the offspring feeding upon it, even though parents secure the carcass.

Reviewer #2: Reviewer comments for PLOS ONE manuscript PONE-D-21-10116

This manuscript describes an experimental study examining potential lifetime fitness effects transmitted through parental body size and natal environment quality. The study uses the burying beetle Nicrophorus marginatus which uses the carcasses of dead vertebrates as breeding resource. The authors generated multigenerational effects by varying the size of both parents and the size of the carcass in a parental generation and monitored subsequent effects on the lifetime fitness of female offspring when breeding on carcasses of different size. There was no evidence that parental body size or natal resource size had an effect on lifetime fitness of offspring measured as lifespan, lifetime number of offspring and number of offspring in the first brood.

This study addresses a gap in our understanding of maternal effects by examining whether such effects actually translate into differences in offspring fitness. This study therefore builds constructively upon prior work which has shown consequences for offspring phenotype but in proxies for fitness rather than fitness itself. Overall, I found this to be a clear, well-written and well-motivated study. However, I have some concerns about how these results would play out in the natural ecological context of these beetles. I also have some lingering questions about the statistical analyses and decisions in the experimental design.

Main comments

1. My main concern is to do with the ecological context of the study. As the authors acknowledge in their discussion their experimental design removed competition over carcasses. However, competition is likely to be a very important component of lifetime fitness in these beetles. This is because carcasses are required for reproduction and therefore only beetles that are able to successfully compete and win control of a carcass will be able to produce any offspring at all. Furthermore, body size is the key determinant of success in such competition. In other words – only offspring of sufficient size to be competitive will be capable of securing any reproductive success/fitness at all.

This means that the most important link between maternal effects and offspring fitness is through effects on competitive ability (mediated through body size) rather than the ability to rear offspring in a competition free environment. Thus, by divorcing the study from this natural context the authors may be underestimating the potential importance of these maternal effects to offspring fitness. That is - although the authors show that multigenerational effects do not influence offspring’s lifetime fitness in the absence of competition – it is possible that in a more natural context (that includes competition) such multigenerational effects may be very important.

The authors do acknowledge this point in their discussion (lines: 271-288). However, I think this caveat needs to be worded more clearly and more strongly (not least for the benefit of readers unfamiliar with burying beetle ecology). For example, in their discussion the authors somewhat dismiss the importance of competition by arguing that population density & carcass availability are likely to fluctuate and that therefore competition (and any selection on body size) will be periodical. However, surely this is only true if there are years where carcasses are so abundant that small beetles are able to secure them without competition. Is such a scenario likely? It’s hard to say! This argument also ignores the fact that when suitable carcasses are scarce (which I would imagine is not uncommon even if there is variation) then any selection will be very strong – as only suitably large beetles will be able to gain any reproductive success at all.

It would be nice to see the authors acknowledge more clearly the role of competition in determining offspring fitness in this system.

2. I wonder why the authors chose to analyse their data using parental size as a single factor with four levels (large♀-large♂, large♀-small♂, … etc.). This approach assumes that the effects of parental body size are the same for both sexes and that there are no interactive effects of male and female body size. Given that the authors varied both male and female size separately in a crossed design wouldn’t a more informative approach have been to include male size and female size as separate factors (each with two levels) and also to include the interaction between the two?

3. Can the authors provide justification for the particular range of carcass sizes used in the study? For example, are N. marginatus typically found on both 20 & 40 g carcasses in the wild?

The reason I ask is because although larger carcasses provide more resources they are also potentially harder for the beetles to bury and prepare. Therefore, a carcass that is too large may represent a challenge to reproduction. I assume this is not the case, but it would be reassuring to know that these beetles are not being presented with a challenge they are unlikely to be adapted to.

4. I may be misunderstanding the results here but did the authors find that offspring reared by larger females (or on larger carcasses) eclosed into larger adults in this study? One lines 226-229 they reference finding such an effect from a previous study but it was not clear to me whether the same effect was detected here.

5. In a similar vein some of the data that appeared to be collected is not presented in the results. For example, it would be interesting to see if the proxies for offspring fitness that are sometimes used by other studies (e.g. offspring body mass at dispersal) present a different pattern as the measures for lifetime number of offspring. This might reinforce the authors argument that proxies based on offspring phenotype are not reliable measures of offspring fitness.

6. Could you provide information on the number of reproductive bouts that females in second generation achieved before they died? Based on the number of offspring in the first bout vs lifetime number of offspring it seems like females are breeding 2 or 3 times? Is that correct? It would be useful to know how many times a female is able to breed under these ideal circumstances (well fed, ready supply of mates, ready supply of carcasses and no competition) because as I argued earlier – it seems likely that in burying beetles some individuals will die without ever having secured a carcass to breed which is why potential maternal effects on body size might be more important.

7. Females in the second generation always bred on the same size carcasses throughout their lifespan (either small or large). I understand the rational behind this (as varying carcass size between bouts would make the experiment very unwieldy) but I wonder if the authors found any evidence that consistently breeding on a high or low quality resource influenced reproductive decisions in any way? For example, do females that keep getting small carcasses decide that things are not going to get better and so invest more (i.e. produce more offspring) on their second or third small carcass than they do on the first? This is likely beyond the scope of the current paper but I am curious if the authors have considered this at all.

Minor comments

1. A diagram of the experimental design would be useful. The methods are explained very clearly but a visual representation of the two generation set up might be helpful.

2. Line 281-284: Is this line referring to the fitness of the female parent or the fitness of her adult offspring? The preceding statement seems to be referring to the fitness of offspring – which I think should be the focus of this paragraph – but this line seems to refer to the fitness of the female parent. Can you clarify this?

3. Line 226: Typo – the period after “beetles” should be a comma I think.

4. Line 197-199: It would be helpful to clarify why this particular interaction was included. If I understand correctly, it is because it allows the authors to test if parents “prime” their offspring for reproduction on a particular carcass size – which is one way that multigenerational effects may act. For example, if female offspring reared on a 40g carcass produced more offspring when breeding on a 40g (in comparison to female offspring reared on 20g breeding on 40g).

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

PLoS One. 2021 Jul 7;16(7):e0253885. doi: 10.1371/journal.pone.0253885.r002

Author response to Decision Letter 0

7 Jun 2021

of the current environment, such as size of the current carcass. Any such multigenerational effects could thus be masked by the influence of current environment. In other words, it is not clear to me why we should expect to see multigenerational effects in burying beetles. I suggest that you make a stronger case and clarifying the arguments for why this species provides a good system to investigate multigenerational effects.

Our goal in this paper is not to suggest that burying beetles provide a good system in which to find adaptive multigenerational effects. Many multigenerational effects have been documented in burying beetles, including anticipatory effects, and it has been suggested that these already documented effects might translate into increased fitness. We simply wanted to test whether that link to fitness (i.e., larger number of offspring in a lifetime) exists. To make this clear we added the following.

“Clearly, multigenerational effects on offspring size in burying beetles may be transmitted through both parental size and carcass size (i.e., natal environment). The implied prediction is that these multigenerational effects are anticipatory and adaptive [4] such that larger offspring would produce more offspring over their lifetime and thus express increased fitness. However, multigenerational effects may not be adaptive for offspring, rather they can evolve only to increase fitness of the parents [4]. Whether multigenerational effects on body size in burying beetles are adaptive for offspring and translate into increased fitness of offspring is not known. “

We believe this statement clearly lays out our objective and satisfies the reviewer’s comment without

overstating our hypothesis.

Done

Good point, we have modified the sentence as follows. “We find no evidence that multigenerational effects from larger parents or larger natal carcasses contribute to increased fitness of offspring.”

We agree that this idea of distinguishing what type of multigenerational effects exist in burying beetles should be introduced in the introduction rather than at the end of the discussion. Accordingly, we have added some text in the introduction that introduces the idea of predicting that these effects could be anticipatory and adaptive for offspring, or they could be adaptive only for the parents following distinctions made in citation number 4 (Marshall and Uller 2007). We have modified our objectives statement to specify that we are testing for adaptive effects that would affect lifetime fitness of offspring. The text now reads:

In this study we tested whether multigenerational effects of parental size and natal carcass size that result in increased offspring size in the burying beetle Nicrophorus marginatus [65] also cause an increase in lifetime fitness of offspring (i.e., they are adaptive [4]).”

We think this change clarifies our intent in the study.

We do consider this a multigenerational effect and others have suggested that it is a multigenerational effect; however, like many aspects of fitness it can be seen as potentially affecting both parental and offspring fitness. These distinctions are discussed in reference number 4, and are somewhat beyond the scope of the current paper. Although we appreciate the idea, we have not altered our statement because the discussion of this idea is tangential to our main focus.

Reviewer #2: Reviewer comments for PLOS ONE manuscript PONE-D-21-10116

experimental design. Main comments

without competition. Is such a scenario likely? It’s hard to say! This argument also ignores the fact that when suitable carcasses are scarce (which I would imagine is not uncommon even if there is variation) then any selection will be very strong – as only suitably large beetles will be able to gain any reproductive success at all.

It would be nice to see the authors acknowledge more clearly the role of competition in determining offspring fitness in this system.

Point well taken! In response we have followed the suggestion of the reviewer and increased our discussion of the potential role of competition for carcasses in conferring fitness. In our expanded discussion of this point we have included three points that we think bear on this idea of strong and pervasive competition as a characteristic of burying beetle biology in the following paragraph.

“ We acknowledge that competitive ability linked to individual body size may confer a fitness advantage under some circumstances, especially if access to carcasses for reproduction is frequently contested, and if body size is often linked to success in obtaining control of carcasses. However, at least three lines of evidence suggest that competition for carcasses may not be a strong determinant of fitness. First, competition for carcasses is dependent on the density of beetles and the availability of small vertebrate carcasses at both large and small scales. Densities of beetles and small vertebrate carcasses fluctuate dramatically among years [74,75]. Similarly, when we trap beetles for this and other studies, we find variation in the number of beetles captured in a given trap, and a range of sizes of both males and females. This spatial variation in number and body size and the temporal variation in beetle numbers and carcass numbers among and within years suggests that competition for

carcasses is likely a local phenomenon. All beetles in a given area are not present and competing for every carcass. Although large beetles may win at carcasses where they compete, some carcasses will have many competitors, and some will have few. Also, when beetles breed on a carcass, they are effectively removed from the potentially competing population for at least two weeks. Thus, the competitive environment is best represented by a mosaic of local carcass availability and local beetle distribution and availability. The outcome is a range of opportunities for beetles of many sizes to be successful at finding and breeding on a carcass. Second, burying beetles exhibit alternative reproductive strategies such that fitness can be obtained by males and females acting as satellites at the carcass burial site or mating prior to finding a carcass [76-78]. If only large individuals can gain access to and reproduce successfully on carcasses, then alternative strategies would not evolve, and body size would be more strongly constrained by selection. Alternative reproductive strategies and a range of body sizes in natural populations suggest that being large is not the only way to be successful in competition for carcasses. Third, in a previous study, we measured competitive ability to gain a carcass based on size in both male and female burying beetles [65]. The relationship differed by sex such that for females, the size difference between competitors had to be much larger for body size to be an important determinant of competitive outcomes. Even for males, there was some non-zero probability of the smaller competitor winning the carcass, except at the largest size difference [65].

Other studies on burying beetles have reported corroborating effects of beetle sizes found on carcasses in natural systems [33]. Body size may be a strong determinant of success in competing for carcasses, but in many contests, priority effects and stochasticity or “luck” may be equally or more important. Although competition for carcasses provides a plausible mechanism for generating fitness effects from multigenerational effects, we urge caution in suggesting that this is a strong and pervasive effect. We simply do not know enough about the frequency and intensity of competition for carcasses in natural systems to be confident in asserting the relative importance of body size.”

We have elaborated our discussion of this idea and included these additional reasons for caution in suggesting that competition for carcasses may be an adaptive reason to expect strong fitness effects of body size.

2. I wonder why the authors chose to analyse their data using parental size as a single factor with four levels (large -large , large -small , … etc.). This approach assumes that the effects of parental body size are the same for both sexes and that there are no interactive effects of male and female body size. Given that the authors varied both male and female size separately in a crossed design wouldn’t a more informative approach have been to include male size and female size as separate factors (each with two levels) and also to include the interaction between the two?

Yes, that would seem obvious, and we appreciate the suggestion because it reminded us that we had not provided sufficient detail in our methods section. We have now included additional information about our choice for the analysis. We have previously analyzed and published the results from the first part (first-generation) of this experiment where we used the factorial design of the parental body size in the way that the reviewer suggested. In that paper, none of the interactions that resulted from treating male and female size as a factorial were significant, so we did not include the interactions in the final analysis of the study. For this study, given the added complexity of including treatments from the second generation, we chose not to analyze the parental size data as a factorial, but rather as 4 combinations. Thus, our highest order interaction is a three-way interaction rather than a four-way interaction and those interactions were tested (they were not significant) and removed (except for one two-way interaction) to provide additional statistical discrimination for main effects. Also,

because there were no significant interactions in the earlier analysis and none in the current analysis, it is unlikely that we would gain any additional insight by keeping parental body size as a factorial effect based on sex. We have added text to explain this choice in analysis as follows.

“We used results from this first-generation experiment to test for effects of body size of parents (male and female separately) and carcass size on their reproductive output and offspring traits [65]. In the first-generation experiment female body size generated significant effects on offspring body size, but male size had no effect on offspring traits and there were no significant interactions between male and female body size [65]. For this reason, we included parental size treatments as four independent treatments in analysis of the second-generation experiment (this paper) rather than as a factorial.

This reduced the complexity of the second-generation analysis by eliminating some two-way and three-way, and all four-way interactions.”

3. Can the authors provide justification for the particular range of carcass sizes used in the study? For example, are N. marginatus typically found on both 20 & 40 g carcasses in the wild?

Based on a previous study N. marginatus has equal lifetime fitness on a range of carcass sizes from 20 to 40 grams. Thus, both carcass sizes are within the range of carcass sizes they are able to process and utilize. Also, the fact that 40g carcasses yielded higher number of offspring compared to 20g carcasses suggests that beetles were able to fully utilize the larger carcass. We have added text to clarify our choice of carcass size as follows.

“We chose 20g and 40g carcass sizes based on a previous study that tested multiple carcass sizes from 5g to 50 g. The 20g and 40g sizes were both within the range of carcass sizes whereon N. marginatus experienced equally high reproductive success [69].”

4. I may be misunderstanding the results here but did the authors find that offspring reared by larger females (or on larger carcasses) eclosed into larger adults in this study? On lines 226-229 they reference finding such an effect from a previous study but it was not clear to me whether the same effect was detected here.

We have previously published results from the first part (first-generation) of the study reported here (Smith and Belk 2018; citation 65 in the old draft) including that larger females produced larger offsapring. The current analysis is based on the second-generation results. We have now clarified the relationship between these two analyses that represent first-generation and second-generation results as follows.

“We used results from this first-generation experiment to test for effects of body size of parents (male and female separately) and carcass size on reproductive output and offspring traits [65]. In the first- generation experiment female body size generated significant effects on offspring body size, but male size had no effect on offspring traits and there were no significant interactions between male and female body size [65]. For this reason, we included parental size treatments as four independent treatments in analysis of the second-generation experiment (this paper) rather than as a factorial.

This reduced complexity of the second-generation analysis by eliminating some two-way and three- way, and all four-way interactions.”

In the current study (second-generation) we did not test for this effect (i.e., larger females produce larger offspring) because it had already been established in the first generation and it was not our purpose here to inspect phenotype of the offspring, but rather fitness (number of offspring) of the second-generation females.

Once again, results of phenotype of offspring were reported in the previous paper as described above (Smith and Belk 2018). In the current analysis we only reported fitness effects. However, the effect of pronotum width of the offspring was included in each analysis, and it was only significant in the analysis of lifespan. We discuss this effect in the first paragraph of the discussion, and show that the added lifetime for larger individuals does not equate to increased fitness. Thus, we have indicated that the proxy of body size is not a reliable measure of fitness.

Number of reproductive bouts for females in the second-generation experiment ranged from 1 to 5 with a mean of 2.9, and we have included this information in the methods section that explains the second-generation experiment. We agree that in natural systems it is unlikely that females are able to breed as the dominant female on a carcass more than 1 or 2 times. For this reason, we included the number of offspring in the first bout as a measure of fitness. In response to the first question above we have provided several reasons why competitive ability arising from differences in body size may not always be a reasonable expectation for generating increased fitness. We added the following text to the discussion.

“In natural environments, number of successful reproductive bouts may be fewer than that in our

non-competitive lab environment. For this reason, we included number of offspring in the first bout as a potentially more natural alternative to measure lifetime reproductive success. Patterns were the same whether we measured fitness as lifetime number of offspring or number of offspring in the first bout, suggesting that even if females reproduce on only one carcass during their lifetime, there is still no effect of parental body size or natal carcass size.”

consistently breeding on a high or low quality resource influenced reproductive decisions in any way? For example, do females that keep getting small carcasses decide that things are not going to get better and so invest more (i.e. produce more offspring) on their second or third small carcass than they do on the first? This is likely beyond the scope of the current paper but I am curious if the authors have considered this at all.

This is an interesting question, but as noted by the reviewer it is not within the scope of the current paper. We have addressed this effect in a previous paper, and there is an effect of the size of carcass first obtained on subsequent reproductive decisions. See:

Billman, E, CJ, Creighton, MC Belk. 2014. Prior experience affects allocation to current reproduction in a burying beetle. Behavioral Ecology, 25: 813-818.

Minor comments

1. A diagram of the experimental design would be useful. The methods are explained very clearly but a visual representation of the two generation set up might be helpful.

We have considered this suggestion, but we feel that a diagram might be redundant with the already long explanatory text. If the editor feels a diagram is warranted, we would be happy to create one.

We clarified the statement to refer to fitness of offspring as follows: “Thus, large body size of a female beetle may translate into increased lifetime fitness in her offspring in a natural environment because larger female offspring are able to win access to more and larger carcasses, and thus produce more offspring.”

3. Line 226: Typo – the period after “beetles” should be a comma I think.

Done

4. Line 197-199: It would be helpful to clarify why this particular interaction was included. If I

understand correctly, it is because it allows the authors to test if parents “prime” their offspring for reproduction on a particular carcass size – which is one way that multigenerational effects may act. For example, if female offspring reared on a 40g carcass produced more offspring when breeding on a 40g (in comparison to female offspring reared on 20g breeding on 40g).

Thank you for this suggestion. That idea captures our intent better than we had previously. We have modified the sentence to read as follows: “This interaction was of interest because of the significant effect of current carcass size on fitness measures, and the possibility of a multigenerational effect that natal carcass size might provide some “priming” for efficiency of use of a similar carcass size.

PLoS One. doi: 10.1371/journal.pone.0253885.r003

Decision Letter 1

William David Halliday

15 Jun 2021

No evidence for increased fitness of offspring from multigenerational effects of parental size or natal carcass size in the burying beetle Nicrophorus marginatus

PONE-D-21-10116R1

Dear Dr. Belk,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

William David Halliday, Ph.D.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Reviewer #1: The authors have responded to all the concerns I raised during the first round of revisions and I have no additional comments. I think that this paper will be an excellent addition to the field and I look forward to its publication.

Reviewer #2: (No Response)

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

PLoS One. doi: 10.1371/journal.pone.0253885.r004

Acceptance letter

William David Halliday

28 Jun 2021

PONE-D-21-10116R1

No evidence for increased fitness of offspring from multigenerational effects of parental size or natal carcass size in the burying beetle Nicrophorus marginatus

Dear Dr. Belk:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

If we can help with anything else, please email us at plosone@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. William David Halliday

Academic Editor

PLOS ONE

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

All the data used in this study are available from the Dryad database (DOI: https://doi.org/10.5061/dryad.1vhhmgqt0).

[pone.0253885.ref001] 1.Rutledge JJ, Robison OW, Eisen EJ, Legates JE. Dynamics of genetic and maternal effects in mice. J Anim Sci. 1972; 35(5): 911–8. doi: 10.2527/jas1972.355911x [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref002] 2.Lande R, Kirkpatrick M. Selection response in traits with maternal inheritance. Genet Res. 1990; 55(3): 189–97. doi: 10.1017/s0016672300025520 [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref003] 3.Rossiter MC. Incidence and consequences of inherited environmental effects. Annu Rev Ecol Syst. 1996; 27: 451–76. [Google Scholar]

[pone.0253885.ref004] 4.Marshall DJ, Uller T. When is a maternal effect adaptive? Oikos. 2007; 116: 1957–63. [Google Scholar]

[pone.0253885.ref005] 5.Bernardo J. Maternal effects in animal ecology. Am Zool. 1996; 36(2): 83–105. [Google Scholar]

[pone.0253885.ref006] 6.Fox C, Mousseau T. Maternal effects as adaptations for transgenerational phenotypic plasticity in insects. In: Maternal Effects as Adaptions. 1998. p. 159–77. [Google Scholar]

[pone.0253885.ref007] 7.Bicho RC, Santos FCF, Scott-Fordsmand JJ, Amorim MJB. Multigenerational effects of copper nanomaterials (cuonms) are different of those of cucl2: exposure in the soil invertebrate Enchytraeus crypticus. Sci Rep. 2017; 7(1): 1–7. doi: 10.1038/s41598-016-0028-x [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0253885.ref008] 8.Schür C, Zipp S, Thalau T, Wagner M. Microplastics but not natural particles induce multigenerational effects in Daphnia magna. Environ Pollut. 2020; 260: 113904. doi: 10.1016/j.envpol.2019.113904 [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref009] 9.Fox CW, Thakar MS, Mousseau TA. Egg size plasticity in a seed beetle: an adaptive maternal effect. Am Nat. 1997; 149(1): 149–63. [Google Scholar]

[pone.0253885.ref010] 10.Boots M, Roberts KE. Maternal effects in disease resistance: poor maternal environment increases offspring resistance to an insect virus. Proc R Soc B Biol Sci. 2012; 279(1744): 4009–14. [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0253885.ref011] 11.Steiger S. Bigger mothers are better mothers: disentangling size-related prenatal and postnatal maternal effects. Proc R Soc B Biol Sci. 2013; 280(1766): 20131225. doi: 10.1098/rspb.2013.1225 [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0253885.ref012] 12.Bloch Qazi MC, Miller PB, Poeschel PM, Phan MH, Thayer JL, Medrano CL. Transgenerational effects of maternal and grandmaternal age on offspring viability and performance in Drosophila melanogaster. J Insect Physiol. 2017; 100: 43–52. doi: 10.1016/j.jinsphys.2017.05.007 [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref013] 13.Vinogradova EB, Reznik SY. Influence of a single (stepwise) change in photoperiod and female age on larval diapause in the blowfly. Entomol Rev. 2002; 82(9): 1190–6. [Google Scholar]

[pone.0253885.ref014] 14.Prasad NG, Shakarad M, Rajamani M, Joshi A. Interaction between the effects of maternal and larval levels of nutrition on pre-adult survival in Drosophila melanogaster. Evol Ecol Res. 2003; 5(6): 903–11. [Google Scholar]

[pone.0253885.ref015] 15.Opit GP, Throne JE. Influence of maternal age on the fitness of progeny in the rice weevil, Sitophilus oryzae (coleoptera: curculionidae). Environ Entomol. 2007; 36(1): 83–9. doi: 10.1603/0046-225x(2007)36[83:iomaot]2.0.co;2 [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref016] 16.Singh K, Omkar. Effect of parental ageing on offspring developmental and survival attributes in an aphidophagous ladybird, Cheilomenes sexmaculata. J Appl Entomol. 2009; 133(7): 500–4. [Google Scholar]

[pone.0253885.ref017] 17.Smallegange IM. Effects of paternal phenotype and environmental variability on age and size at maturity in a male dimorphic mite. Naturwissenschaften. 2011; 98(4): 339–46. doi: 10.1007/s00114-011-0773-4 [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref018] 18.Ducatez S, Baguette M, Stevens VM, Legrand D, Fréville H. Complex interactions between paternal and maternal effects: parental experience and age at reproduction affect fecundity and offspring performance in a butterfly. Evolution. 2012; 66(11): 3558–69. doi: 10.1111/j.1558-5646.2012.01704.x [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref019] 19.Mestre L, Bonte D. Food stress during juvenile and maternal development shapes natal and breeding dispersal in a spider. Behav Ecol. 2012; 23(4): 759–64. [Google Scholar]

[pone.0253885.ref020] 20.Vargas G, Michaud JP, Nechols JR. Maternal effects shape dynamic trajectories of reproductive allocation in the ladybird Coleomegilla maculata. Bull Entomol Res. 2012; 102(5): 558–65. doi: 10.1017/S000748531200020X [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref021] 21.Pick JL, Ebneter C, Hutter P, Tschirren B. Disentangling genetic and prenatal maternal effects on offspring size and survival. Am Nat. 2016; 188(6): 628–39. doi: 10.1086/688918 [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref022] 22.Bock MJ, Jarvis GC, Corey EL, Stone EE, Gribble KE. Maternal age alters offspring lifespan, fitness, and lifespan extension under caloric restriction. Sci Rep. 2019; 9(1): 1–16. doi: 10.1038/s41598-018-37186-2 [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0253885.ref023] 23.Pierotti R, Clutton-Brock TH. Reproductive success: studies of individual variation in contrasting breeding systems. Condor. 1989; 91(3): 750. [Google Scholar]

[pone.0253885.ref024] 24.Shine R, Reiss MJ. The allometry of growth and reproduction. J Anim Ecol. 1990; 59(3): 1197. [Google Scholar]

[pone.0253885.ref025] 25.Waller JT, Svensson EI. Body size evolution in an old insect order: no evidence for cope’s rule in spite of fitness benefits of large size. Evolution. 2017; 71(9): 2178–93. doi: 10.1111/evo.13302 [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref026] 26.Berger A. Egg weight, batch size and fecundity of the spotted stalk borer, Chilo partellus in relation to weight of females and time of oviposition. Entomol Exp Appl. 1989; 50(3): 199–207. [Google Scholar]

[pone.0253885.ref027] 27.Kim JY. Female size and fitness in the leaf-cutter bee Megachile apicalis. Ecol Entomol. 1997; 22(3): 275–82. [Google Scholar]

[pone.0253885.ref028] 28.Fox CW, Savalli UM. Inheritance of environmental variation in body size: superparasitism of seeds affects progeny and grandprogeny body size via a nongenetic maternal effect. Evolution. 1998; 52: 172–82. doi: 10.1111/j.1558-5646.1998.tb05150.x [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref029] 29.Wainhouse D, Ashburner R, Boswell R. Reproductive development and maternal effects in the pine weevil Hylobius abietis. Ecological Entomology. 2001; 26: 655–61. [Google Scholar]

[pone.0253885.ref030] 30.Fischer K, Zwaan BJ, Brakefield PM. How does egg size relate to body size in butterflies? Oecologia. 2002; 131(3): 375–9. doi: 10.1007/s00442-002-0913-9 [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref031] 31.Vargas G, Michaud JP, Nechols JR. Cryptic maternal effects in Hippodamia convergens vary with maternal age and body size. Entomol Exp Appl. 2013; 146(2): 302–11. [Google Scholar]

[pone.0253885.ref032] 32.Kojima W. Variation in body size in the giant rhinoceros beetle Trypoxylus dichotomus is mediated by maternal effects on egg size. Ecol Entomol. 2015; 40(4): 420–7. [Google Scholar]

[pone.0253885.ref033] 33.Scott MP, Traniello JFA. Behavioural and ecological correlates of male and female parental care and reproductive success in burying beetles (Nicrophorus spp.). Anim Behav. 1990; 39(2): 274–83. [Google Scholar]

[pone.0253885.ref034] 34.Barneche DR, Burgess SC, Marshall DJ. Global environmental drivers of marine fish egg size. Glob Ecol Biogeogr. 2018; 27(8): 890–8. [Google Scholar]

[pone.0253885.ref035] 35.Bartlett J, Ashworth CM. Brood size and fitness in Nicrophorus vespilloides (coleoptera: Silphidae). Behav Ecol Sociobiol. 1988; 22(6): 429–34. [Google Scholar]

[pone.0253885.ref036] 36.Sieber DJ, Paquet M, Smiseth PT. Joint effects of brood size and resource availability on sibling competition. Anim Behav. 2017; 129: 25–30. [Google Scholar]

[pone.0253885.ref037] 37.Kawecki TJ. Adaptive plasticity of egg size in response to competition in the cowpea weevil, Callosobruchus maculatus (coleoptera: Bruchidae). Oecologia. 1995; 102(1): 81–5. doi: 10.1007/BF00333313 [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref038] 38.Visser ME. The influence of competition between foragers on clutch size decisions in an insect parasitoid with scramble larval competition. Behav Ecol. 1996; 7(1): 109–14. [Google Scholar]

[pone.0253885.ref039] 39.Creighton JC. Population density, body size, and phenotypic plasticity of brood size in a burying beetle. Behav Ecol. 2005; 16(6): 1031–6. [Google Scholar]

[pone.0253885.ref040] 40.Woelber BK, Hall CL, Howard DR. Environmental cues influence parental brood structure decisions in the burying beetle Nicrophorus marginatus. J Ethol. 2018; 36(1): 55–64. [Google Scholar]

[pone.0253885.ref041] 41.McGregor PK, Krebs JR, Perrins CM. Song repertoires and lifetime reproductive success in the great tit (Parus major). Am Nat. 1981; 118(2): 149–59. [Google Scholar]

[pone.0253885.ref042] 42.MacColl ADC, Hatchwell BJ. Determinants of lifetime fitness in a cooperative breeder, the long-tailed tit Aegithalos caudatus. J Anim Ecol. 2004; 73(6): 1137–48. [Google Scholar]

[pone.0253885.ref043] 43.Felsenstein J, Lewontin RC. The genetic basis of evolutionary change. Evolution. 1975; 29(3): 587. [Google Scholar]

[pone.0253885.ref044] 44.Allendorf FW, Leary RF. Heterozygosity and fitness in natural populations of animals. Conserv Biol Sci Scarcity Divers. 1986; 57: 58–72. [Google Scholar]

[pone.0253885.ref045] 45.Gilbert NE, Endler JA. Natural selection in the wild. J Anim Ecol. 1987; 56(2): 719. [Google Scholar]

[pone.0253885.ref046] 46.Wang S, Hard JJ, Utter F. Genetic variation and fitness in salmonids. Conserv Genet. 2002; 3: 321–33. [Google Scholar]

[pone.0253885.ref047] 47.Jervis MA, Ferns PN. The timing of egg maturation in insects: ovigeny index and initial egg load as measures of fitness and of resource allocation. Oikos. 2004. 107; 449–61. [Google Scholar]

[pone.0253885.ref048] 48.South A, Lewis SM. The influence of male ejaculate quantity on female fitness: a meta-analysis. Biol Rev. 2011; 86(2): 299–309. doi: 10.1111/j.1469-185X.2010.00145.x [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref049] 49.Kant R, Minor MA, Trewick SA, Sandanayaka WRM. Body size and fitness relation in male and female Diaeretiella rapae. BioControl. 2012; 57(6): 759–66. [Google Scholar]

[pone.0253885.ref050] 50.Langley PA, Pimley RW, Mews AR, Flood MET. Effect of diet composition on feeding, digestion, and reproduction in Glossina morsitans. J Insect Physiol. 1978; 24(3): 233–8. [Google Scholar]

[pone.0253885.ref051] 51.Gustafsson S, Rengefors K, Hansson LA. Increased consumer fitness following transfer of toxin tolerance to offspring via maternal effects. Ecology. 2005; 86(10): 2561–7. [Google Scholar]

[pone.0253885.ref052] 52.Paquet M, Smiseth PT. Females manipulate behavior of caring males via prenatal maternal effects. Proc Natl Acad Sci U S A. 2017; 114(26): 6800–5. doi: 10.1073/pnas.1619759114 [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0253885.ref053] 53.Coakley CM, Nestoros E, Little TJ. Testing hypotheses for maternal effects in Daphnia magna. J Evol Biol. 2018; 31(2): 211–6. doi: 10.1111/jeb.13206 [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0253885.ref054] 54.Fetherston IA, Scott MP, Traniello JFA. Parental care in burying beetles: the organization of male and female brood‐care behavior. Ethology. 1990; 85(3): 177–90. [Google Scholar]

[pone.0253885.ref055] 55.Rauter CM, Moore AJ. Do honest signalling models of offspring solicitation apply to insects? Proc R Soc B Biol Sci. 1999; 266(1429): 1691–6. [Google Scholar]

[pone.0253885.ref056] 56.Trumbo ST. Infanticide, sexual selection and task specialization in a biparental burying beetle. Anim Behav. 2006; 72(5): 1159–67. [Google Scholar]

[pone.0253885.ref057] 57.Otronen M. The effect of body size on the outcome of fights in burying beetles (Nicrophorus). Ann Zool Fennici. 1988; 25(2): 191–201. [Google Scholar]

[pone.0253885.ref058] 58.Scott MP. Brood guarding and the evolution of male parental care in burying beetles. Behav Ecol Sociobiol. 1990; 26(1): 31–9. [Google Scholar]

[pone.0253885.ref059] 59.Scott MP. The benefit of paternal assistance in intra- and interspecific competition for the burying beetle, Nicrophorus defodiens. Ethol Ecol Evol. 1994; 6(4): 537–43. [Google Scholar]

[pone.0253885.ref060] 60.Eggert AK, Sakaluk SK. Benefits of communal breeding in burying beetles: a field experiment. Ecol Entomol. 2000; 25(3): 262–6. [Google Scholar]

[pone.0253885.ref061] 61.Müller JK, Eggert AK, Dressel J. Intraspecific brood parasitism in the burying beetle, Nicrophorus vespilloides (coleoptera: Silphidae). Anim Behav. 1990; 40(3): 491–9. [Google Scholar]

[pone.0253885.ref062] 62.Safryn SA, Scott MP. Sizing up the competition: do burying beetles weigh or measure their opponents? J Insect Behav. 2000; 13(2): 291–7. [Google Scholar]

[pone.0253885.ref063] 63.Hopwood PE, Moore AJ, Royle NJ. Nutrition during sexual maturation affects competitive ability but not reproductive productivity in burying beetles. Funct Ecol. 2013; 27(6): 1350–7. [Google Scholar]

[pone.0253885.ref064] 64.Lee VE, Head ML, Carter MJ, Royle NJ. Effects of age and experience on contest behavior in the burying beetle, Nicrophorus vespilloides. Behav Ecol. 2014; 25(1): 172–9. doi: 10.1093/beheco/art101 [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0253885.ref065] 65.Smith AN, Belk MC. Does body size affect fitness the same way in males and females? a test of multiple fitness components. Biol J Linn Soc. 2018; 124(1): 47–55. [Google Scholar]

[pone.0253885.ref066] 66.Lock JE, Smiseth PT, Moore PJ, Moore AJ. Coadaptation of prenatal and postnatal maternal effects. Am Nat. 2007; 170(5): 709–18. doi: 10.1086/521963 [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref067] 67.Paquet M, Parenteau C, Ford LE, Ratz T, Richardson J, Angelier F, et al. Females adjust maternal hormone concentration in eggs according to male condition in a burying beetle. Horm Behav. 2020; 121: 104708. doi: 10.1016/j.yhbeh.2020.104708 [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref068] 68.Richardson J, Ross J, Smiseth PT. Food deprivation affects egg laying and maternal care but not offspring performance in a beetle. Behav Ecol. 2019; 30(5): 1477–87. [Google Scholar]

[pone.0253885.ref069] 69.Meyers PJ. Variation in resource utilization and cost of reproduction for two burying beetle species [Master’s Thesis]. Provo (UT): Brigham Young University; 2014.

[pone.0253885.ref070] 70.Smith AN, Belk MC, Creighton JC. Residency time as an indicator of reproductive restraint in male burying beetles. PLoS One. 2014; 9(10): 109165 doi: 10.1371/journal.pone.0109165 [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0253885.ref071] 71.Hopwood PE, Moore AJ, Tregenza T, Royle NJ. Niche variation and the maintenance of variation in body size in a burying beetle. Ecol Entomol. 2016; 41(1): 96–104. [Google Scholar]

[pone.0253885.ref072] 72.Creighton JC, Heflin ND, Belk MC. Cost of reproduction, resource quality, and terminal investment in a burying beetle. Am Nat. 2009; 174(5): 673–84. doi: 10.1086/605963 [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref073] 73.Rauter CM, McGuire MJ, Gwartney MM, Space JE. Effect of population density and female body size on number and size of offspring in a species with size-dependent contests over resources. Ethology. 2010; 116(2): 120–8. [Google Scholar]

[pone.0253885.ref074] 74.Scott MP. The ecology and behavior of burying beetles. Annu Rev of Entomol. 1998; 43: 595–618. doi: 10.1146/annurev.ento.43.1.595 [DOI] [PubMed] [Google Scholar]

[pone.0253885.ref075] 75.Smith RJ, Hines A, Richmond S, Merrick M, Drew A, Fargo R. Altitudinal variation in body size and population density of Nicrophorus investigator (coleoptera: Silphidae). Environ Entomol. 2000; 29(2): 290–8. [Google Scholar]

[pone.0253885.ref076] 76.Eggert AK. Alternative male mate-finding tactics in burying beetles. Behav Ecol. 1992; 3(3): 243–54. [Google Scholar]

[pone.0253885.ref077] 77.Müller JK, Eggert AK. Paternity assurance by “helpful” males: adaptations to sperm competition in burying beetles. Behav Ecol Sociobiol. 1989; 24(4): 245–9. [Google Scholar]

[pone.0253885.ref078] 78.Müller JK, Braunisch V, Hwang W, Eggert AK. Alternative tactics and individual reproductive success in natural associations of the burying beetle, Nicrophorus vespilloides. Behav Ecol. 2007; 18(1): 196–203. [Google Scholar]

PERMALINK

No evidence for increased fitness of offspring from multigenerational effects of parental size or natal carcass size in the burying beetle Nicrophorus marginatus

Ethan P Damron

Ashlee N Smith

Dane Jo

Mark C Belk

Roles

Abstract

Introduction

Methods

Source of burying beetles

Experimental design

Analysis

Results

Table 1. Results of mixed model analysis of covariance for three fitness measures for N. marginatus.

Table 2. Least squares means and upper and lower confidence intervals for main effects of current carcass size and the interaction between current carcass size and natal carcass size in N. marginatus.

Discussion

Acknowledgments

Data Availability

Funding Statement

References

Decision Letter 0

William David Halliday

Roles

Author response to Decision Letter 0

Decision Letter 1

William David Halliday

Roles

Acceptance letter

William David Halliday

Roles

Associated Data

Data Availability Statement

ACTIONS

PERMALINK

RESOURCES

Cite

Add to Collections

PERMALINK

No evidence for increased fitness of offspring from multigenerational effects of parental size or natal carcass size in the burying beetle Nicrophorus marginatus

Ethan P Damron

Ashlee N Smith

Dane Jo

Mark C Belk

Roles

Abstract

Introduction

Methods

Source of burying beetles

Experimental design

Analysis

Results

Table 1. Results of mixed model analysis of covariance for three fitness measures for N. marginatus.

Table 2. Least squares means and upper and lower confidence intervals for main effects of current carcass size and the interaction between current carcass size and natal carcass size in N. marginatus.

Discussion

Acknowledgments

Data Availability

Funding Statement

References

Decision Letter 0

William David Halliday

Roles

Author response to Decision Letter 0

Decision Letter 1

William David Halliday

Roles

Acceptance letter

William David Halliday

Roles

Associated Data

Data Availability Statement

ACTIONS

PERMALINK

RESOURCES

Similar articles

Cited by other articles

Links to NCBI Databases