Background: Life history theory predicts that during the lifespan of an organism, resources are allocated to either growth, somatic maintenance or reproduction. Resource allocation trade-offs determine the evolution and ecology of different life history strategies and define an organisms’ position along a fast–slow continuum in interspecific comparisons. Labord’s chameleon (Furcifer labordi) from the seasonal dry forests of Madagascar is the tetrapod species with the shortest reported lifespan (4–9 months). Previous investigations revealed that their lifespan is to some degree dependent on environmental factors, such as the amount of rainfall and the length of the vegetation period. However, the intrinsic mechanisms shaping such a fast life history remain unknown. Environmental stressors are known to increase the secretion of glucocorticoids in other vertebrates, which, in turn, can shorten telomeres via oxidative stress. To investigate to what extent age-related changes in these molecular and cellular mechanisms contribute to the relatively short lifetime ofF. labordi, we assessed the effects of stressors indirectly via leukocyte profiles (H/L ratio) and quantified relative telomere length from blood samples in a wild population in Kirindy Forest. We compared our findings with the sympatric, but longer-lived sister speciesF.cf.nicosiai,which exhibit the same annual timing of reproductive events, and with wild-caughtF. labordithat were singly housed under ambient conditions.Results: We found that H/L ratios were consistently higher in wildF. labordicompared toF.cf.nicosiai. Moreover,F. labordialready exhibited relatively short telomeres during the mating season when they were 3–4 months old, and telomeres further shortened during their post-reproductive lives. At the beginning of their active season, telomere length was relatively longer inF.cf.nicosiai, but undergoing rapid shortening towards the southern winter, when both species gradually die off. CaptiveF. labordishowed comparatively longer lifespans and lower H/L ratios than their wild counterparts.Conclusion: We suggest that environmental stress and the corresponding accelerated telomere attrition have profound effects on the lifespan ofF. labordiin the wild, and identify physiological mechanisms potentially driving their relatively early senescence and mortality.

Designer dogs—the result of intentionally crossbreeding purebred dogs, and specifically poodle mixes (a cross between a poodle and a second breed)—have rapidly grown in popularity in recent years