Telomere dynamics in a lizard with morph‐specific reproductive investment and self‐maintenance

Abstract

Telomeres in human fibroblasts shorten progressively during in vitro culturing and trigger replicative senescence. Furthermore, shortened telomeres can be used as biomarkers of disease. These observations have led to the suggestion that telomere dynamics may also be associated with viability and selection for life history variation in non-human taxa. Model systems to examine this suggestion would particularly benefit from the coexistence of multiple phenotypes within the same species with different life history trade-offs, since those could be compared in terms of telomere characteristics. This scenario also provokes the classic question of why one morph does not have marginally higher fitness and replaces the others. One explanation is that different morphs have different reproductive tactics with equal relative fitness. In Australian painted dragons (Ctenophorus pictus), males differ in head color, the presence or absence of a gular bib, and reproductive expenditure. Red males out-compete yellow males in dominance contests, while yellow males copulate quickly and have higher success in sperm competition than red males. Males with bibs better defend partners against rival matings, at the cost of loss of body condition. We show that yellow-headed and bib-less males have longer telomeres than red, blue and bibbed males, suggesting that telomere length is positively associated with higher investment into self-maintenance and less reproductive expenditure. K E Y W O R D Salternative reproductive tactics, Ctenophorus pictus, painted dragon lizard, TA-65, trade-offs

Evolutionary ecology of telomeres: a review

“…In accordance with predictions, morphs with high investment in reproduction also had shorter telomeres, which captures the relatively lower levels of somatic maintenance (using qPCR; Fig. ) …”

“…This mating behavior typically takes place in (D) large competitive aggregations emerging from hibernation in limestone sick holes in spring (© CRF, from Ref. ).…”

“…showed that, when telomeres were longer, regrowth of flight feather was faster in TA‐65–treated individuals and, hence, longer telomeres were concluded to be indicators of overall health and viability. A similar experiment on ectothermic dragon lizards ( C. pictus ), using elevated TA‐65 dosage to compensate for lower night metabolic rate, had no effect on telomere length (using qPCR) . Clearly, a method of reliably manipulating telomere length that has few pleiotropic effects would be a boon for those interested in elucidating the causality of telomeres in the context of evolutionary ecology.…”

“…3). 68 The underlying reasons for sexual differences in telomere length have been a contentious issue 69 and are still fiercely debated. 8 However, one thing is clear: when two sexes differ in key traits, such as reproductive investment, heterogamety, aging trajectories, sexual dimorphism, and disease susceptibility, the prediction is that telomere dynamics should differ between the sexes; we expect differences among sexes depending on their current and past evolutionary biology.…”

Distinct telomere differences within a reproductively bimodal common lizard population

“…Recent studies have linked telomere dynamics to various stressful conditions, both in vitro and in vivo (Barnes, Fouquerel, & Opresko, 2018;Cram, Monaghan, Gillespie, & Clutton-Brock, 2017;Debes et al, 2016;Monaghan, 2014;Olsson et al, 2018). Moreover, a recent study on Australian painted dragons (Ctenophorus pictus) found that telomere dynamics differed between individuals with different reproductive and life-history tactics (Rollings et al, 2017). It is therefore possible that differing reproductive costs associated with oviparity or viviparity will also influence patterns of telomere loss.…”