Phylogenetic Relationships and Tempo of Early Diversification in Anolis Lizards

We examine phylogenetic relationships among anoles using mitochondrial DNA sequences from the NADH dehydrogenase subunit 2 gene (ND2) and five transfer-RNA genes representing 1,455 alignable base positions and 866 phylogenetically informative characters (parsimony criterion). We also present 16 morphological characters for phylogenetic analysis. Our analyses yielded poorly-supported nodes deep in the anole tree but many well-supported nodes for more recent phylogenetic divergences. We test the hypothesis that the major clades of anoles form a hard polytomy and present a general statistical framework for testing hypotheses of simultaneous branching of lineages by using molecular sequence data. Our results suggest that rapid diversification early in the evolutionary history of anoles explains why numerous researchers have had difficulty reconstructing well-supported dichotomous phylogenetic trees for anoles.