Molecular Phylogeny and Historical Biogeography of Pacific Island Boas (Candoia)
The enigmatic biogeography of Pacific island boas of the genus Candoia is examined using DNA sequence variation from a portion of the mitochondrial cytochrome b gene. Estimates of the phylogenetic relationships and genetic distances between Candoia and the Old World (Sanzinia) and New World boids (Boa, Corallus, and Epicrates) suggest that a recent dispersal event from the Americas is not responsible for Candoia's Papuan distribution. Multiple populations from the three Candoia species are sampled to distinguish whether substantial evolutionary partitions exist within species as a result of colonization patterns or geographical barriers and to assess whether genetic partitions are concordant with species boundaries. In all analyses, Candoia and the Madagascan Sanzinia are sister taxa, and C. bibroni is basal to C. aspera and C. carinata. Mean sequence divergences between Candoia and the other boid genera Sanzinia, Corallus, Epicrates, and Boa are 0.19, 0.23, 0.24, and 0.25, respectively. Within Candoia, mean interspecific sequence divergence ranges from 0.13, between C. aspera and C. bibroni, to 0.16 for both C. aspera/C. carinata and C. bibroni/C. carinata pairwise comparisons. Large intraspecific sequence divergence (up to 0.13 within C. carinata) exists within Candoia species demonstrating deep separations corresponding to patterns of island colonization and geographic barriers in New Guinea.Abstract

Map of localities for the Candoia used in this study. Numbers 1, 2, 5, and 6 designate Candoia carinata populations. Numbers 3 and 4 represent Candoia aspera populations. Candoia bibroni samples are from localities 7 and 8

Phylogram of the maximum parsimony tree (A) and maximum likelihood tree (B) obtained from PAUP* searches using the Python reticulatus sequences as the outgroups. Numbers at nodes represent bootstrap proportions for 5000 and 100 pseudoreplicates for parsimony and likelihood analyses, respectively. Bootstrap proportions above the lines correspond to the TI/TV weighted analysis and numbers below the lines correspond to the bootstrap proportions to the transversion only analysis. Bootstrap proportions less than 50% are not shown. The maximum likelihood tree (B) differs from the single most parsimonious tree only in the arrangement of Candoia aspera populations. For both analyses Sanzinia is the sister taxon to Candoia