Evolution of disjunct distributions among wet-zone species of the Indian subcontinent: Testing various hypotheses using a phylogenetic approach

Abstract

Disjunct distributions among wet-zone taxa of the Indian subcontinent have intrigued biologists for decades. Most authors have invoked variations of either the dispersal or the vicariance model to explain disjunct distribution. However, some have noted that incorrect taxonomy, due to convergence in morphological characters, can erroneously suggest disjunct distribution. An appropriate approach to test these models (vicariance, dispersal and convergence) is to use molecular phylogenetic methods. A survey of recent molecular phylogenetic studies on Indian systems with disjunct distribution suggests that convergence may be quite common. Therefore, I propose that the first step in studying disjunct distributions is to determine if the observed pattern is real (true disjunct) and not due to convergence, i.e. an artifact of incorrect taxonomy (false disjunct).