Amphibians live longer at higher altitudes but not at higher latitudes

Abstract

Why and how organisms differ in life-history strategies across their range is a long-standing topic of interest to evolutionary ecologists. Although many studies have addressed this issue for several life-history traits, such as body size and clutch size, very few have been made for some others traits, including longevity. In the present study, we performed a comparative study aiming to develop general patterns of geographical variation in longevity of urodele and anuran amphibians using published information on demographic age derived from skeletochronology. We conducted within-species meta-analyses using datasets of two (ten urodele and 12 anuran species) and multiple (two urodele and nine anuran species) spatially-separated populations and found that maturation, mean, and maximum age all increased with altitude but not with latitude in each sex of both amphibian groups. This geographical pattern held true across 33 urodele and 86 anuran species at common body sizes, independent of phylogeny. It is likely that metabolic rate, reproductive investment, and mortality risk, which are the key factors that affect longevity as suggested by ageing theory, vary systemically along altitudinal gradients but not along latitudinal gradients. The evolutionary causes behind these puzzling patterns deserve further investigation. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society.