Table 1.
Summary of the statistics and of the potential driving factors compiled in the meta-analysis. For each study, the sex difference in TL (g), its variance and its sample size are reported. The tissue sampled is reported as RBC for red blood cells, WBC for white blood cells and other for all other types of tissue. The method of TL measurement is reported as TRFS for telomere restriction fragment followed by a Southern blot, TRFI for telomere restriction fragment followed by an in-gel hybridization, and qPCR. See electronic supplementary material, Methods and Results for further information.
| species | study | g | variance | sample size | tissue | method |
|---|---|---|---|---|---|---|
| BIRDS | ||||||
| Acrocephalus arundinaceus | [29] | −0.086 | 0.059 | 68 | RBC | qPCR |
| Acrocephalus sechellensis | [30] | 0.174 | 0.005 | 837 | RBC | qPCR |
| Aptenodytes patagonicus | [31] | 0.115 | 0.08 | 50 | RBC | qPCR |
| Aptenodytes patagonicus | [32] | −0.158 | 0.038 | 106 | RBC | qPCR |
| Aptenodytes patagonicus | [33] | −0.094 | 0.027 | 146 | RBC | qPCR |
| Branta leucopsis | [34] | 0.678 | 0.141 | 34 | RBC | TRFS |
| Calidris alpina | [35] | −0.177 | 0.178 | 24 | RBC | TRFI |
| Corvus monedula | [36] | 0.242 | 0.084 | 48 | RBC | TRFI |
| Diomedea exulans | [37] | 0.423 | 0.068 | 60 | RBC | TRFS |
| Fregata minor | [38] | −0.076 | 0.229 | 22 | RBC | TRFI |
| Hirundo rustica | [39] | 0.17 | 0.031 | 130 | RBC | qPCR |
| Larus crassirostris | [40] | −0.278 | 0.051 | 82 | RBC | TRFS |
| Larus crassirostris | [41] | −0.214 | 0.072 | 72 | RBC | TRFS |
| Leucophaeus pipixcan | [42] | −0.437 | 0.205 | 20 | RBC | qPCR |
| Luscinia svecica | [43] | −0.15 | 0.042 | 97 | RBC | qPCR |
| Macronectes giganteus | [44] | −0.653 | 0.092 | 47 | RBC | TRFS |
| Macronectes halli | [24] | −1.016 | 0.124 | 37 | RBC | TRFS |
| Parus caeruleus | [45] | 0.384 | 0.079 | 56 | RBC | qPCR |
| Parus major | [46] | −0.483 | 0.099 | 42 | RBC | TRFI |
| Parus major | [47] | 0.483 | 0.053 | 79 | RBC | qPCR |
| Parus major | [47] | 0.018 | 0.054 | 76 | RBC | qPCR |
| Riparia riparia | [35] | −0.158 | 0.267 | 16 | RBC | TRFI |
| Rissa tridactyla | [48] | 0.457 | 0.111 | 38 | RBC | TRFS |
| Sterna hirundo | [49] | 0.139 | 0.017 | 233 | RBC | TRFI |
| Strigops habroptila | [50] | 0.6 | 0.062 | 67 | RBC | TRFS |
| Strix aluco | [51] | 0.06 | 0.026 | 158 | RBC | qPCR |
| Tachycineta bicolor | [52] | 0.187 | 0.057 | 82 | RBC | qPCR |
| Tachymarptis melba | [53] | 0.044 | 0.041 | 96 | RBC | qPCR |
| Taeniopygia guttata | [54] | −0.307 | 0.229 | 19 | RBC | TRFI |
| Taeniopygia guttata | [55] | 0.375 | 0.042 | 99 | RBC | qPCR |
| Taeniopygia guttata | [55] | 0.128 | 0.052 | 79 | RBC | qPCR |
| Thalassarche melanophrys | [56] | 0.091 | 0.079 | 51 | other | TRFS |
| Turdus merula | [57] | −0.206 | 0.102 | 40 | RBC | TRFI |
| Turdus merula | [57] | −0.607 | 0.192 | 22 | RBC | TRFI |
| Uria lomvia | [58] | 0.33 | 0.235 | 35 | RBC | qPCR |
| Uria lomvia | [58] | 0.956 | 0.147 | 47 | RBC | TRFS |
| Uria lomvia | [59] | 0.578 | 0.101 | 60 | RBC | TRFS |
| Vultur gryphus | [60] | 0.566 | 0.21 | 20 | RBC | qPCR |
| MAMMALS | ||||||
| Capreolus capreolus | [61] | −0.023 | 0.055 | 73 | WBC | qPCR |
| Capreolus capreolus | [61] | −0.154 | 0.061 | 66 | WBC | qPCR |
| Crocuta crocuta | [62] | −0.771 | 0.091 | 66 | WBC | TRFI |
| Elephas maximus | [63] | −0.335 | 0.077 | 120 | WBC | qPCR |
| Eliomys quercinus | [64] | −0.382 | 0.259 | 16 | other | qPCR |
| Glis glis | [65] | 0.432 | 0.213 | 20 | other | qPCR |
| Macaca fascicularis | [66] | 0.11 | 0.202 | 20 | other | TRFS |
| Macaca fascicularis | [66] | −0.186 | 0.192 | 21 | other | TRFS |
| Macaca fascicularis | [66] | 0.238 | 0.201 | 20 | other | TRFS |
| Macaca fascicularis | [66] | −0.819 | 0.219 | 20 | other | TRFS |
| Macaca fascicularis | [66] | −0.615 | 0.221 | 19 | other | TRFS |
| Macaca fascicularis | [66] | −0.069 | 0.191 | 21 | other | TRFS |
| Macaca fascicularis | [66] | 0.63 | 0.233 | 18 | other | TRFS |
| Macaca fascicularis | [66] | −0.088 | 0.191 | 21 | other | TRFS |
| Macaca fascicularis | [66] | 0 | 0.202 | 20 | other | TRFS |
| Macaca fascicularis | [66] | 0.101 | 0.2 | 20 | other | TRFS |
| Macaca fascicularis | [66] | 0.571 | 0.21 | 20 | other | TRFS |
| Macaca fascicularis | [66] | 0.345 | 0.314 | 13 | other | TRFS |
| Macaca mulatta | [67] | −0.251 | 0.084 | 48 | other | TRFS |
| Macaca mulatta | [67] | −0.027 | 0.083 | 48 | WBC | TRFS |
| Macaca mulatta | [67] | −0.282 | 0.084 | 48 | other | TRFS |
| Macaca mulatta | [67] | −0.14 | 0.084 | 48 | other | TRFS |
| Mandrillus sphinx | [68] | 1.284 | 0.04 | 120 | WBC | qPCR |
| Meles meles | [69] | 0.13 | 0.011 | 360 | WBC | qPCR |
| Mus musculus | [70] | 0.055 | 0.243 | 17 | WBC | qPCR |
| Mus spretus | [71] | −0.48 | 0.049 | 84 | other | TRFS |
| Mus spretus | [71] | −0.73 | 0.045 | 94 | other | TRFS |
| Mus spretus | [71] | −0.681 | 0.039 | 110 | other | TRFS |
| Mus spretus | [71] | −0.818 | 0.036 | 127 | other | TRFS |
| Neophoca cinerea | [72] | −0.052 | 0.167 | 25 | other | qPCR |
| Ovis aries | [73] | −0.024 | 0.01 | 481 | WBC | qPCR |
| FISH | ||||||
| Cyprinus carpio | [74] | 0.133 | 0.056 | 73 | other | qPCR |
| Menidia menidia | [75] | −0.074 | 0.173 | 29 | other | qPCR |
| Menidia menidia | [75] | −0.082 | 0.136 | 38 | other | qPCR |
| Pungitius pungitius | [76] | −0.336 | 0.049 | 83 | other | qPCR |
| Salmo salar | [77] | −0.251 | 0.062 | 67 | other | qPCR |
| Salmo salar | [78] | 0.437 | 0.047 | 89 | other | qPCR |
| Heterodontus portusjacksoni | [25] | −0.495 | 0.214 | 20 | other | aqPCR |
| Heterodontus portusjacksoni | [25] | 0.45 | 0.182 | 24 | other | qPCR |
| Heterodontus portusjacksoni | [25] | −0.31 | 0.202 | 20 | other | TRFS |
| REPTILES | ||||||
| Alligator mississippiensis | [79] | 0.131 | 0.167 | 24 | RBC | TRFI |
| Chlamydosaurus kingii | [80] | −0.239 | 0.102 | 112 | RBC | qPCR |
| Lacerta agilis | [81] | −0.323 | 0.025 | 161 | RBC | TRFS |
| Liasis fuscus | [82] | −0.909 | 0.123 | 45 | RBC | TRFS |
| Thamnophis sirtalis | [22] | −0.638 | 0.06 | 72 | RBC | qPCR |
| Zootoca vivipara | [83] | −0.621 | 0.436 | 10 | RBC | TRFS |
| Zootoca vivipara | [83] | 0.254 | 0.403 | 10 | RBC | TRFS |
| Zootoca vivipara | [83] | 0.687 | 0.424 | 10 | RBC | TRFS |
| Zootoca vivipara | [83] | 0.257 | 0.403 | 10 | RBC | TRFS |
| Zootoca vivipara | [83] | 0.591 | 0.417 | 10 | RBC | TRFS |
| Zootoca vivipara | [83] | 0.601 | 0.418 | 10 | RBC | TRFS |
| Zootoca vivipara | [83] | 0.157 | 0.401 | 10 | RBC | TRFS |
| Zootoca vivipara | [83] | −0.216 | 0.402 | 10 | RBC | TRFS |
| Zootoca vivipara | [83] | −0.39 | 0.408 | 10 | RBC | TRFS |
| Zootoca vivipara | [83] | 0.033 | 0.4 | 10 | RBC | TRFS |