Species and morphological diversification in Viperidae snakes: patterns and processes

Abstract

Different groups of organisms might be characterized by high species diversity and/or high morphological disparity. These two parameters are commonly used to define adaptive radiations, and in theory the same intrinsic characteristic of a given lineage could generate both species and morphological diversity. On the other hand, the correlation between taxonomic and morphological diversity is not an obligatory evolutionary trajectory. This study aims to explore patterns of species and morphological diversification in a highly diverse snake lineage, the family Viperidae, and the processes that could potentially generate these patterns. To achieve this goal, three different approaches will be used. First, we are going to analyzed if the lineages with higher diversification rates are also those with the higher morphological disparity. Second, we are going to explore one of the factors that are commonly associated with diversity dynamics: the spatial distribution of the species within a given clade. More specifically, we are going to test if species's (and genera) geographic range size and overlap degree could potentially explain differences among the diversification rates and morphological disparity of different clades. Finally, in the third approach, we are going to study the evolution of head shape in new world pitvipers, in order to elucidate the possible relationship between morphology and diet. Diversification rates of Viperidae lineages and their morphospace are going to be estimated using molecular phylogenies and museum specimens as well as data from the literature. Geographic distribution maps of species and genera are going to be elaborated, and we are going to use both linear and geometric morphometric to analyze how head shape evolved and how it relates to diet. (AU)