Shorter telomeres precede population extinction in wild lizards

Abstract

Identifying the early warning signals of catastrophic extinctions has recently become a central focus for ecologists, but species’ functional responses to environmental changes remain an untapped source for the sharpening of such warning signals. Telomere length (TL) analysis represents a promising molecular tool with which to raise the alarm regarding early population decline, since telomere attrition is associated with aging processes and accelerates after a recurrent exposure to environmental stressors. In the southern margin of their range, populations of the common lizard (Zootoca vivipara) recently became extinct at lowest elevations due to changes in climate conditions. However, the proximal signals involved in these demographic declines are still unknown. Here, we sampled 100 yearling lizards from 10 natural populations (n = 10 per population) along an extinction risk gradient. Relative lizard abundance dramatically dropped over 12 years in low-altitude populations characterized by warmer ambient temperatures and higher body growth of lizards early in life. A non-linear relationship was found between TL and population extinction risk, with shorter telomeres in populations facing high risk of extinction when compared to non-threatened ones. Our results identify TL as a promising biomarker and imply that population extinctions might be preceded by a loop of physiological aging.

Reduction in baseline corticosterone secretion correlates with climate warming and drying across wild lizard populations

“…In the longitudinal study, the initial model included the quadratic effect of time of day, fixed effects of population, sex and sampling session, and first‐ and second‐order interaction terms. In the studied populations, lizard morphology strongly varies among and between populations, sex and age class as previously demonstrated (e.g., Chamaillé‐Jammes et al., ; Dupoué, Rutschmann, Le Galliard, Clobert, et al., ; Massot, Clobert, Pilorge, Lecomte, & Barbault, ). Therefore to avoid multicollinearity, lizard morphological indexes were not included in the model selection as we aimed to specifically test the influence of environmental conditions on baseline corticosterone levels independently from variation in morphology.…”

“…During the searches, people randomly scan the populations to find lizards that are then captured by hand. Lizard abundance was calculated in summers 2005, 2015 and 2017 based on the number of lizards captured divided by the total time spent searching, the number of people capturing and the area of the study site (Dupoué, Rutschmann, Le Galliard, Clobert, et al., ). We used the relative changes in abundance to determine the IUCN status of each population, and we identified two populations extremely at risk, one population at risk and 11 nonthreatened populations (Supporting Information Table S1).…”

“…Given that several variables were highly correlated and related to population collapse, we computed the relative changes in abundance, T min and the altitude together in a principal component analysis [package ade4 (Dray & Dufour, )]. We used the first axis (PC 1 ) as a composite score of extinction risk as it was mainly determined by the relative changes in lizard abundance (Supporting Information Table S4), as this integrative score of population decline has been demonstrated to correlate with molecular markers of physiological stress (Dupoué, Rutschmann, Le Galliard, Clobert, et al., ). We compared all models, including additive effects of each environmental covariate or the PC 1 score (six variables), as well as two‐way interactions with age and sex (cross‐sectional study, Supporting Information Table S5) and two‐way interactions with sex and sampling session (longitudinal study, Supporting Information Table S6).…”

“…), which may influence corticosterone levels. However, we focused here on the environmental covariates that are associated with population decline (Dupoué, Rutschmann, Le Galliard, Clobert, et al., ). In each population, we sampled the representative demographic structure by capturing females and males from two age classes, including reproductive adults and nonreproductive yearlings.…”

Isolation and characterization of fourteen polymorphic microsatellite markers in the viperine snake Natrix maura

“…Ectotherms represent more than 98% of animal species and are the more likely to be affected because of direct physiological sensitivity to climate conditions (Deutsch et al, 2008;Dupoué et al, 2017;Sinervo et al, 2010). When the conservation status of a given population is uncertain, genetic studies constitute an indirect and valuable approach to assess the impacts of these environmental threats on levels of population genetic diversity and structure, effective dispersal, demographic status and possible past and future responses to global change (Segelbacher et al, 2010).…”