Understanding species - level primate diversity in Madagascar

Abstract

Over the past couple of decades Madagascar has witnessed an explosion in the number of primate species generally recognized. Much of this proliferation can be traced less to increasing knowledge of the lemur fauna than to the complete replacement of biological notions of the species by the Phylogenetic Species Concept (PSC), which views species as irreducible diagnosable units. The consequent focus on autapomorphy (unique possession of morphological and molecular derived features) as ‘the’ criterion for species recognition has led to the almost complete disappearance of lemur subspecies from Madagascar faunal lists; yet subspecies are an expected result of the evolutionary forces that gave rise to the island’s current pattern of biodiversity. Thanks in part to the perspective introduced by the PSC, it has become clear both that there is much more species - level diversity among Madagascar’s lemurs than was evident only a couple of decades ago, and that this diversity is much more complexly structured than we had thought. But it does not appear to be aptly reflected in the hard - line procedural adoption of the PSC across the board, a move that typically results in fifty-percent inflation in species numbers relative to those yielded by biological concepts. I argue here that the reflexive wholesale application of the PSC to Madagascar’s lemurs is inappropriate from both systematic and conservation standpoints, and that a return to biological species concepts, and to the corresponding criteria for species recognition, will allow us to attain a much fuller and more nuanced appreciation of lemur diversity at low taxonomic levels.