Taylor Gregory T, McQueen Alexandra, Eastwood Justin R, Dupoué Andréaz, Wong Bob B M, Verhulst Simon, Peters Anne
School of Biological Sciences Monash University Clayton Victoria Australia.
Present address: Centre for Integrative Ecology Deakin University Burwood Victoria Australia.
Ecol Evol. 2024 Mar 1;14(3):e11088. doi: 10.1002/ece3.11088. eCollection 2024 Mar.
Life-history theory predicts that reproductive investments are traded-off against self-maintenance. Telomeres, the protective caps on the ends of chromosomes, offer a promising avenue for assessing life-history trade-offs, as they shorten in response to stressors and are predictive of the remaining lifespan. In males, testosterone frequently mediates life-history trade-offs, in part, through its effects on sexual ornamentation, which is an important aspect of reproductive investment. However, studies of within-individual associations between telomere dynamics and sexual ornamentation are limited in number and have produced mixed results. Furthermore, most such studies have been observational, making it difficult to discern the nature of any causal relationship. To address this, we used short-acting testosterone implants in free-living male superb fairy-wrens () to stimulate the production of a sexual ornament: early moult into a costly blue breeding plumage. We found no evidence that elevated testosterone, and the consequent earlier moult into breeding plumage, accelerated telomere shortening. We therefore followed up with a systematic review and two meta-analyses (28 studies, 54 effect sizes) exploring the associations between telomeres and (1) testosterone and (2) sexual ornamentation. In line with our experimental findings, neither meta-analysis showed an overall correlation of testosterone or sexual ornamentation with telomere length or telomere dynamics. However, meta-regression showed that experimental, compared to observational, studies reported greater evidence of trade-offs. Our meta-analyses highlight the need for further experimental studies to better understand potential responses of telomere length or telomere dynamics to testosterone or sexual ornamentation.
生活史理论预测，生殖投资与自我维持之间存在权衡。端粒是染色体末端的保护帽，为评估生活史权衡提供了一条有前景的途径，因为它们会因应激源而缩短，并能预测剩余寿命。在雄性中，睾酮常常部分地通过其对性装饰的影响来介导生活史权衡，而性装饰是生殖投资的一个重要方面。然而，关于端粒动态与性装饰之间个体内关联的研究数量有限，且结果不一。此外，大多数此类研究都是观察性的，因此难以辨别任何因果关系的本质。为了解决这个问题，我们在自由生活的雄性华丽细尾鹩莺（）身上使用了短效睾酮植入物，以刺激一种性装饰的产生：提前换羽为代价高昂的蓝色繁殖羽。我们没有发现证据表明睾酮水平升高以及随之而来的提前换羽为繁殖羽会加速端粒缩短。因此，我们随后进行了一项系统综述和两项荟萃分析（28项研究，54个效应量），以探究端粒与（1）睾酮和（2）性装饰之间的关联。与我们的实验结果一致，两项荟萃分析均未显示睾酮或性装饰与端粒长度或端粒动态之间存在总体相关性。然而，元回归分析表明，与观察性研究相比，实验性研究报告了更多权衡的证据。我们的荟萃分析强调需要进一步开展实验研究，以更好地理解端粒长度或端粒动态对睾酮或性装饰的潜在反应。
