Sex‐specific telomere length and dynamics in relation to age and reproductive success in Cory’s shearwaters

Abstract

Individuals in free-living animal populations generally differ substantially in reproductive success, lifespan and other fitness-related traits, but the molecular mechanisms underlying this variation are poorly understood. Telomere length and dynamics are candidate traits explaining this variation, as long telomeres predict a higher survival probability and telomere loss has been shown to reflect experienced "life stress." However, telomere dynamics among very long-lived species are unresolved.Additionally, it is generally not well understood how telomeres relate to reproductive success or sex. We measured telomere length and dynamics in erythrocytes to assess their relationship to age, sex and reproduction in Cory's shearwaters (Calonectris borealis), a long-lived seabird, in the context of a long-term study. Adult males had on average 231 bp longer telomeres than females, independent of age. In females, telomere length changed relatively little with age, whereas male telomere length declined significantly. Telomere shortening within males from one year to the next was three times higher than the interannual shortening rate based on cross-sectional data of males. Past long-term reproductive success was sex-specifically reflected in agecorrected telomere length: males with on average high fledgling production were characterized by shorter telomeres, whereas successful females had longer telomeres, and we discuss hypotheses that may explain this contrast. In conclusion, telomere length and dynamics in relation to age and reproduction are sex-dependent in Cory's shearwaters and these findings contribute to our understanding of what characterises individual variation in fitness. K E Y W O R D Sageing, biomarker, fitness, life-history, reproduction, survival | 1345 BAUCH et Al.

Longer telomeres during early life predict higher lifetime reproductive success in females but not males

“…Few studies have examined whether the relationships between telomeres and reproductive success differ between the sexes. Consistent with our results, a recent study in Cory's shearwaters (Calonectris borealis), reported that females with longer telomeres in adulthood produced more offspring, while the opposite was true in males [51], but it is unclear how telomeres and longevity or lifetime fitness are related in this species or whether this results from early-life events as suggested here, or from processes that act only in adulthood.…”

Wing: A suitable nonlethal tissue type for repeatable and rapid telomere length estimates in bats

“…Our study shows that R. aegyptiacus females have longer rTL across all tissues than males, corresponding to results found in previous studies across different study systems (Barrett & Richardson, 2011; Bauch et al., 2020; Rollings et al., 2017; Watson et al., 2017). It is likely that differing life histories between males and females play a part in their differing TLs (Kotrschal et al., 2007; Rollings et al., 2017).…”

Costs of reproduction and migration are paid in later return to the colony, not in physical condition, in a long-lived seabird

“…The primary explanation for these observations is that somatic maintenance is prioritised in K-strategists as future survival and reproductive potential are favoured over current reproductive output (Stearns 1992). Analysis of telomere shortening, a biomarker for ageing, within the same experimental set-up also support these observations as manipulated reproductive effort had no significant impact on telomere length from 1 year to the next (Bauch et al 2020). The cost for self-maintenance appears to be paid by delaying arrival date, as reflected by the earlier arrival of males whose reproductive effort was experimentally reduced, irrespective of migratory strategy.…”