Recent posts on Anole Annals evaluated the taxonomic implications of Nicholson et al.’s [1] new systematics, yet their manuscript included similarly bold interpretations of anole biogeography and the chronology of their diversification. Nicholson et al. claim that a single genus genus concept for anoles can stifle “scientific communication regarding evolutionary events” and used their new multi-genera taxonomy “to propose a bold hypothesis of the biogeographic history of the family within the constraints of the phylogeny inferred here, the latest known fossils, and a paleogeographic interpretation of the deep history of the West Indies, North America, Mesoamerica, and South America.” My goal today is to address if their phylogenetic dating analysis is capable of delivering on such claims.
Anoles are characterized by a sparse and poorly understood fossil record. Any attempt to elucidate the evolutionary history and biogeography of anoles depends on neontological data in the form of DNA sequences from extant species. Nicholson et al. utilized molecular clock dating methods to hypothesize about the temporal history of anoles. They calibrated their tree with two amber fossils containing lizards identifiable as anoles. They attribute the first, Anolis dominicanus, to the clade containing A. aliniger, A. chlorocyanus, A. coelestinus, and A. singularis and assign an age of 23 million years before present (mypb) to this clade. They use the second second fossil, A. electrum, to calibrate the split between A. limifrons and A. zeus to 28 mybp. With this background in hand, let’s turn to evaluating their results.
For the sake of a critical evaluation, I have centered the remainder of the post around a three questions I would have asked had I been selected to review this paper during the peer review process.
