Environmental stress shapes life-history variation in the swelled-vented frog (Feirana quadranus)

Abstract

Understanding how environmental stress modifies life-history traits of vertebrates is highly important for their conservation and management. Amphibians, in particular, have experienced rapid declines in abundance due to their relatively low mobility and strict physiological constraints. Therefore, it is important to understand how amphibians have evolved to cope with environmental stress, and to identify the relevant life-history traits that mediate these dynamics. In this study, we quantified the variation of life-history traits (i.e., body size and age) across the distributional range for a mountain frog species, Feirana quadranus, and identified potential impacts of environmental stress on these traits. Based on the similarity of environmental variables describing bioclimatic and ultraviolet-B radiation conditions from a hierarchical cluster analysis, all populations were assigned to three distinct groups: low, intermediate and high environmental harshness regimes. We found no significant difference in age structure among environmental regimes, with 68% of individuals being between four and six years old. The average age of individuals did not differ among regimes or between sexes, but snout-vent length (SVL) and hind limb length differed significantly among both. When environmental stress was represented along the principle component axes, we found a significant correlation between environmental stress and hind limb length, but not for age or SVL. Our results help us understand potential impacts of environmental stress on life-history variation in F. quadranus covering its whole distribution range. Specifically, our findings highlight the adaptive potential of amphibians to changing environmental conditions via life-history variation as a function of environmental stress.