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 lemuri form radiation, drawing on data from morphology, physiology, behaviour and molecular genetics. Almost all possible relationships have been proposed, a nd most nodes have been contested. We present a phylogenetic analysis, usin g several analytical methods, of a partial sequence from the 12S rRNA mitoc hondrial gene. This gene codes for the small ribosomal subunit, and functio nal constraints require that the secondary structure of the molecule is str ongly conserved, which in turn exerts constraints on the primary sequence s tructure. Although previous studies have suggested a very wide range of phy logenetic applicability for this molecule, our results indicate that it is most useful in strepsirrhine primates for estimating relationships among ge nera within families and among relatively recently diverged families (mean sequence divergence about 11%). Relationships among families separated by l arger genetic distances (>12% divergence; e.g. Cheirogaleidae, Daubentoniid ae, Megaladapidae) are difficult to resolve consistently. Our data show str ong support for an Indridae-Lemuridae sister group and for monophyly of the Lemuridae with Varecia as the sister to all other lemurids. They also supp ort, albeit less strongly, sister group relationships between Lemur and Hap alemur within the Lemuridae and between Propithecus and Avahi in the Indrid ae. (C) 2001 The Linnean Society of London.