Species richness and speciation in the genus Lepilemur in northwestern Madagascar

Sportive lemurs of the genus Lepilemur are small, nocturnal folivorous lemurs that are exclusively arboreal and generally have small distribution ranges. Owing to these characteristics, they are particularly negatively affected by deforestation and habitat fragmentation, which is reflected by the recent uplisting of many of the 26 Lepilemur species into one of the threatened categories of the IUCN Red List.

The main aim of this study is to understand the evolutionary mechanisms underlying species richness and speciation processes of the genus Lepilemur in northwestern Madagascar, and to test the predictions of the Inter-River-System biogeographic model of lemur distribution patterns proposed by Olivieri et al. (2007). This study focuses particularly on three Lepilemur taxa: L. sahamalazensis, L. dorsalis and L. mittermeieri, which have their distribution ranges in the northwestern regions of Sofia and Diana. The objectives are to determine their exact distributions, currently unknown; to assess the allopatry or parapatry for L. dorsalis and L. mittermeieri; and to explain the barrier between these two taxa if it exists. A second fundamental aspect of the project consists in the development of noninvasive tools, based on species-specificity of bio-acoustic structures, which will allow species identification in the field.

This paper discusses the results from a two-month preliminary field season, conducted from 1st April to 31st May 2013 in order to explore the mainland forests located between the Andranomalaza (Maetsamalaza) and Maevarano rivers. We established the presence/absence of Lepilemur in different forest fragments of this poorly-known area and collected information about land use classes and land use change using remote sensing techniques.