Biological Sciences, Bishop's University, Sherbrooke, Québec, Canada.
Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada.
Mol Ecol. 2022 Jul;31(14):3812-3826. doi: 10.1111/mec.16533. Epub 2022 Jun 19.
Understanding ageing and the diversity of life histories is a cornerstone in biology. Telomeres, the protecting caps of chromosomes, are thought to be involved in ageing, cancer risks and life-history strategies. They shorten with cell division and age in somatic tissues of most species, possibly limiting lifespan. The resource allocation trade-off hypothesis predicts that short telomeres have thus coevolved with early reproduction, proactive behaviour and reduced lifespan, that is, a fast pace-of-life syndrome (POLS). Conversely, since short telomeres may also reduce the risks of cancer, the anticancer hypothesis advances that they should be associated with slow POLS. Conclusion on which hypothesis best supports the role of telomeres as mediators of life-history strategies is hampered by a lack of study on wild short-lived vertebrates, apart from birds. Using seven years of data on wild Eastern chipmunks Tamias striatus, we highlighted that telomeres elongate with age (n = 204 and n = 20) and do not limit lifespan in this species (n = 51). Furthermore, short telomeres correlated with a slow POLS in a sex-specific way (n = 37). Females with short telomeres had a delayed age at first breeding and a lower fecundity rate than females with long telomeres, while we found no differences in males. Our findings support most predictions adapted from the anticancer hypothesis, but none of those from the resource allocation trade-off hypothesis. Results are in line with an increasing body of evidence suggesting that other evolutionary forces than resource allocation trade-offs shape the diversity of telomere length in adult somatic cells and the relationships between telomere length and life-histories.
理解衰老和生命史的多样性是生物学的基石。端粒是染色体的保护帽，被认为与衰老、癌症风险和生命史策略有关。它们在大多数物种的体细胞分裂和年龄增长过程中会缩短，可能会限制寿命。资源分配权衡假说预测，短端粒因此与早期繁殖、积极行为和寿命缩短相关，即快速生活史综合征 (POLS)。相反，由于短端粒也可能降低癌症风险，抗癌假说认为它们应该与缓慢的 POLS 相关。除了鸟类之外，关于野生短寿命脊椎动物的研究很少，因此，哪种假说最能支持端粒作为生命史策略中介的作用的结论受到了阻碍。利用七年时间对野生东部花栗鼠（Tamias striatus）的数据进行分析，我们发现端粒会随着年龄的增长而延长（n=204 和 n=20），并且在该物种中不会限制寿命（n=51）。此外，端粒的长短与 POLS 的快慢呈性别特异性相关（n=37）。短端粒的雌性比长端粒的雌性首次繁殖的年龄更大，繁殖力更低，而我们在雄性中没有发现差异。我们的研究结果支持大多数来自抗癌假说的预测，但没有一个来自资源分配权衡假说的预测。这些结果与越来越多的证据一致，这些证据表明，除了资源分配权衡之外，其他进化力量也会影响成年体细胞中端粒长度的多样性以及端粒长度与生命史之间的关系。
