Phenotypic and Geographic Variation in Two Co-Distributed Patagonian Lizard Clades (Squamata, Liolaemini)

Abstract

Selective pressures vary throughout the range of a species distribution, thus favoring different phenotypes. Climate gradients in particular exert selection on the ecological and physiological performance of organisms, which often promotes morphological variation. In Patagonia, a region with harsh climatic conditions, the sister genera Phymaturus and Liolaemus include several widely co-distributed clades. One example is the Liolaemus bibronii complex and the Phymaturus patagonicus clade; these lineages differ in both morphological characteristics and life-history strategies. Co-distributed species may be similarly affected by shared environmental variables that predominate in their distributions, including patterns of morphological variation. In this study we identify and compare patterns of morphological variation in relation to geographical distribution. We used body size and head shape of species of the L. bibronii complex and the P. patagonicus clade throughout their distributions in Patagonia, and quantified the relationships between morphological variables with latitude and climatic variables. The results showed co-variation of body size and head shape between latitude and climatic variables in both clades, but these do not follow an evident pattern of morphological variation in co-distributed representatives of sister clades with different life histories and evolutionary characteristics.