Telomere length (TL), typically measured across a sample of blood cells, has emerged as an exciting potential marker of physiological state and of the costs of investment in growth and reproduction within evolutionary ecology. While there is mounting evidence from studies of wild vertebrates that short TL predicts raised subsequent mortality risk, the relationship between reproductive investment and TL is less clear cut, and previous studies report both negative and positive associations. In this study, we examined the relationship between TL and different aspects of maternal reproductive performance in a free-living population of Soay sheep. We find evidence for shorter TL in females that bred, and thus paid any costs of gestation, compared to females that did not breed. However, we found no evidence for any association between TL and litter size. Furthermore, females that invested in gestation and lactation actually had longer TL than females who only invested in gestation because their offspring died shortly after birth. We used multivariate models to decompose these associations into among- and within-individual effects, and discovered that within-individual effects were driving both the negative association between TL and gestation, and the positive association between TL and lactation. This suggests that telomere dynamics may reflect recent physiologically costly investment or variation in physiological condition, depending on the aspect of reproduction being investigated. Our results highlight the physiological complexity of vertebrate reproduction, and the need to better understand how and why different aspects of physiological variation underpinning life histories impact blood cell TL.

中文翻译：

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野生索伊羊雌性繁殖性能与白细胞端粒长度的关系

端粒长度 (TL) 通常在血细胞样本中测量，已成为生理状态以及进化生态学中生长和繁殖投资成本的令人兴奋的潜在标志物。虽然越来越多的野生脊椎动物研究证据表明，短 TL 预示着随后的死亡风险会增加，但生殖投资与 TL 之间的关系并不那么明确，之前的研究报告了消极和积极的关联。在这项研究中，我们检查了自由生活的 Soay 绵羊种群中 TL 与母体繁殖性能不同方面之间的关系。我们发现有证据表明，与未繁殖的雌性相比，繁殖并因此支付了任何妊娠费用的雌性 TL 更短。然而，我们没有发现 TL 和产仔数之间有任何关联的证据。此外，投资于妊娠和哺乳的雌性实际上比只投资于妊娠的雌性具有更长的 TL，因为她们的后代在出生后不久就死亡了。我们使用多变量模型将这些关联分解为个体间和个体内的影响，并发现个体内的影响正在推动 TL 与妊娠之间的负相关以及 TL 与哺乳之间的正相关。这表明端粒动力学可能反映了最近生理上昂贵的投资或生理条件的变化，这取决于所研究的繁殖方面。我们的结果突出了脊椎动物繁殖的生理复杂性，