Phylogenetic relationships among the Malagasy lemuriforms (Primates: Strepsirrhini) as indicated by mitochondrial sequence data from the 12S rRNA gene

Numerous phylogenetic hypotheses have been advanced for the Malagasy lemuriform radiation, drawing on data from morphology, physiology, behaviour and molecular genetics. Almost all possible relationships have been proposed, and most nodes have been contested. We present a phylogenetic analysis, using several analytical methods, of a partial sequence from the 12S rRNA mitochondrial gene. This gene codes for the small ribosomal subunit, and functional constraints require that the secondary structure of the molecule is strongly conserved, which in turn exerts constraints on the primary sequence structure. Although previous studies have suggested a very wide range of phylogenetic applicability for this molecule, our results indicate that it is most useful in strepsirrhine primates for estimating relationships among genera within families and among relatively recently diverged families (mean sequence divergence about 11%). Relationships among families separated by larger genetic distances (>12% divergence; e.g. Cheirogaleidae, Daubentoniidae, Megaladapidae) are difficult to resolve consistently. Our data show strong support for an Indridae - Lemuridae sister group and for monophyly of the Lemuridae with Varecia as the sister to all other lemurids. They also support, albeit less strongly, sister group relationships between Lemur and Hapalemur within the Lemuridae and between Propithecus and Avahi in the Indridae.