Table 1.
Number of effect sizes, studies and the mean (range) sample size of species analysed in the (a) testes and (b) sperm meta-analyses. The total dataset is summarized separately for each meta-analysis followed by a summary that illustrates the distribution of data based on phylum (Arthropoda versus Chordata) and class/subclass of animals included in the analyses.
| meta-analysis | effect sizes | studies | mean n (range) | |
|---|---|---|---|---|
| (a) testes meta-analysis | 99 | 58a | 35.3 (2–776) | |
| phylum | class/subclass | |||
| Arthropoda | Arachnida | 1 | 1 | 8 |
| Insecta | 7 | 5 | 14.6 (2–28) | |
| Chordata | Actinopterygii | 15 | 7 | 27.5 (2–111) |
| Amphibia | 6 | 5 | 40.8 (24–65) | |
| Aves | 24 | 17 | 61.2 (2–776) | |
| Chondrichthyes | 2 | 1 | 12 | |
| Mammalia | 44 | 23 | 28 (2–141) | |
| (b) sperm meta-analysis | 186 | 74 | 42.3 (2–323) | |
| phylum | class/subclass | |||
| Arthropoda | Arachnida | 2 | 1 | 8 |
| Insecta | 23 | 19 | 21.6 (2–127) | |
| Chordata | Actinopterygii | 9 | 5 | 19.3 (7–46) |
| Amphibia | 16 | 4 | 56.2 (22–130) | |
| Aves | 54 | 18 | 48.2 (3–232) | |
| Chondrichthyes | 4 | 1 | 16.5 (16–18) | |
| Mammalia | 74 | 29 | 47.5 (2–226) | |
| Reptilia | 4 | 1 | 25 | |
aNote that the total number of studies is one less than the sum of the number of studies when divided by phylum and class/subclass as one study presented data from two animal classes.