Phylogenetic tree from Castañeda & de Queiroz's concatenated dataset (left), instability of relationships among five major clades resulting from analyses of mtDNA (top center) and nDNA (bottom center), Anolis (Phenacosaurus) heterderma from Juan Salvador Mendoza's Flickr (http://www.flickr.com/photos/ecoterror/page6/) (top right), and geographic distributions for major clades identified by Castañeda and de Queiroz (bottom right).
A few days ago, I discussed a paper that proposes assignment of anoles to a new family called Dactyloidae. Today, I want to call attention to another new paper about anole systematics and taxonomy that involves a clade beginning with ‘dactyl’: the Dactyloa clade of Anolis. The Dactyloa clade includes around 80 species of anoles found across southern Central America, northern South America, and the southern Lesser Antilles. Although most anole biologist believe that its best to continue recognizing the species in this clade as members of a unified Anolis, the Dactyloa clade does seem to represent one of the few genera proposed by Guyer and Savage that is largely monophyletic (albeit with the addition of species previously assigned to Phenacosaurus).
In a paper published in Molecular Phylogenetic and Evolution, Castañeda and de Queiroz generate new phylogenetic trees for this group based on DNA sequence data from three loci (two mitochondrial and one nuclear) sampled across 40 of 82 previously recognized species, two new species, and 12 outgroup taxa. Castañeda and de Queiroz’s analyses of concatenated and individual gene datasets using GARLI and MrBayes recover support for five well-supported and geographically cohesive clades within Dactyloa. Three of these clades closely match groups defined based on previously morphological and biogeographic analyses: Phenacosaurus, the roquet series, and the latifrons series. Two of the clades identified by Castañeda and de Queiroz were not diagnosed by previous morphological analyses, but do make sense biogeographically: one of these clades occurs across the eastern cordillera of the Colombian Andes and the Venezuelan Andes (the “eastern” clade of Dactyloa) and the second can be found across the western and central cordilleras of the Colombian Andes, the western slope of the Equadorian Andies and the Pacific lowlands of Panama, Colombia, and Ecuador (the “western” clade of Dactyloa). The monophyly of two clades previously identified by morphological analyses – the aequatorialis and punctatus series – is strongly rejected by the new molecular data, reaffirming problems that have long plagued taxonomic studies of mainland anoles based on morphological data. Relationships among the five well-supported and geographically-cohesive clades identified by Castañeda and de Queiroz are poorly supported and unstable among analyses, seemingly due to short basal branches. Although their results clearly indicate the need for taxonomic revision of Dactyloa, Castañeda and de Queiroz reasonably suggest that any such revisions should await more comprehensive species-level sampling is available.