Biodiversity, phylogeography, biogeography and conservation: lemurs as an example.

The lemurs of Madagascar represent a spectacular example of adaptive radiation among primates. Given the special setting under which they evolved (i.e. long isolation, geographical location, geological relief), they provide excellent models for study in many realms, and at different levels and scales, including diversity. At the same time, they occur in a 'hottest hot spot' region for biodiversity conservation. Although there is no single definition of biodiversity, the most commonly used units to measure biodiversity are species-species richness, species abundance and, for conservation purposes in particular, species endemism. However, what a species actually is or how, precisely, it should be defined are unresolved issues. Many species concepts have been proposed and several have been used in primatology in recent years. Nowadays, one of the more common approaches to measuring diversity, and eventually inferring species status, is to look at genetic diversity as reflected by mitochondrial DNA differences. Not enough attention has been paid, however, to the different levels at which genetic differences may occur. Lemurs provide instructive examples to highlight the questions involved in species recognition and definition. Using lemurs as examples, I will highlight the strengths and limitations of some analytical tools, including phylogeography and cladistic biogeography and, I will, in particular, emphasize the questions arising at the interface of scientific and conservation perceptions, both of which influence decisions in the field of biodiversity preservation.