TABLE 2.

Features of C. elegans consistent with semelparous reproductive death.

(1) C. elegans hermaphrodites exhibit early, massive pathology affecting organs linked to reproduction (Garigan et al., 2002; Herndon et al., 2002; Ezcurra et al., 2018).

(2) Gut-to-yolk biomass conversion appears to be part of a suicidal reproductive effort that promotes fitness by feeding trophallactic fluid to larval kin (Kern et al., 2021).

(3) Blocking hermaphrodite reproductive maturation (e.g., by germline ablation) suppresses development of such pathologies, and leads to increases in lifespan of a large magnitude (Hsin and Kenyon, 1999; Ezcurra et al., 2018; Kern et al., 2020).

(4) Germline removal in wild-type males, which do not exhibit semelparity-like pathology, does not increase lifespan (McCulloch, 2003).

(5) Caenorhabditis hermaphrodites, which exhibit senescent transformation, are shorter lived than (unmated) Caenorhabditis females, which do not, consistent with reproductive death in the former only (Kern et al., 2020).

(6) Caenorhabditis hermaphrodites vent yolk and lay unfertilized oocytes in large numbers, while Caenorhabditis females do not (Kern et al., 2020).

(7) Germline removal in unmated Caenorhabditis females, which do not exhibit semelparity-like pathology, produces much smaller increases in lifespan than in Caenorhabditis hermaphrodites (Kern et al., 2020).

(8) Germline removal removes the difference in lifespan between Caenorhabditis females and hermaphrodites (Kern et al., 2020).

(9) C. elegans senescent transformation involves source-to-sink type resource remobilization, as seen in semelparous animals and plants (Ezcurra et al., 2018; Kern et al., 2021).

(10) Autophagic processes that enable biomass conversion and resource remobilization contribute to senescent pathogenesis in C. elegans as in semelparous organisms (particularly plants) (Ezcurra et al., 2018; Benedetto and Gems, 2019).

(11) Semelparous senescence occurs earlier in cell compartments or organs that are non-essential for survival and behavior (e.g., the C. elegans intestine) (Ezcurra et al., 2018) than in essential organs (e.g., the C. elegans nervous system) (Herndon et al., 2002).

(12) Semelparous species often have an extended pre-reproductive stage, followed by a very brief reproductive stage (c.f. the dauer stage in C. elegans) (Klass and Hirsh, 1976).