Lineage delimitation and diversification in Nyctibatrachus, an endemic frog genus from the Western Ghats

Abstract

Determining how biodiversity is produced and maintained remains one of the fundamental questions in ecology. The phenomenon of diversification, which occurs via the interplay of speciation and extinction, holds the key to understanding this question. Diversification is crucial to understanding how biodiversity is distributed over and varies across spatial and temporal scales. By and large, studies of diversification are biased towards the Neotropics and temperate regions, with very few studies in the tropics of Asia. This study makes an effort to address this gap by examining the process of diversification in Nyctibatrachus, an endemic anuran genus from the Western Ghats, a biodiversity hotspot in India. Historically, our understanding of anuran diversity in this hotspot and the factors influencing this diversity has been constrained by inadequate knowledge about the large number of undescribed species. This dearth of information about undescribed species is closely related to the problem of species delimitation. It is crucial to delimit species boundaries in a systematic manner, as species are the fundamental units at which evolutionary processes operate. Therefore, I first carry out lineage delimitation in Nyctibatrachus, following which I investigate the process of diversification and its outcomes in this genus. My results suggest that body size disparity seems to be a prominent component of overall diversification process in Nyctibatrachus. Additionally, evolution of this body size diversity may have very well played a major role in structuring Nyctibatrachus assemblages through the process of competitive exclusion and consequent lineage assortment.