In and out of Mesoamerica: temporal divergence of Amazilia hummingbirds pre-dates the orthodox account of the completion of the Isthmus of Panama
We used mitochondrial DNA sequences to reconstruct the phylogenetic relationships of Mesoamerican Amazilia hummingbirds (Trochilidae). The phylogeny was used to identify vicariance scenarios, reconstruct ancestral biogeographical areas, and investigate the role of geological events in generating genetic divergence through vicariance events.
Molecular sequence data were gathered from three mitochondrial genes (ND2, ND5 and 12S) for samples taken within the Mesoamerican region and analysed using maximum parsimony, maximum-likelihood and Bayesian approaches. Statistical dispersal–vicariance analysis (S-DIVA) was used to reconstruct biogeographical areas and changes in distribution during the evolutionary history of Amazilia. The phylogeny was calibrated using fossil dates, mean substitution rates and coalescent-based divergence time inference.
Amazilia can be split into two divergent lineages, with high levels of sequence divergence within some Mesoamerican species. Ancestral area reconstructions favour an ancestral distribution west of the Isthmus of Tehuantepec, with subsequent dispersals east of the isthmus and to South America. Divergence time estimations suggest that major diversification events occurred in the Miocene and Pliocene, corresponding temporally and geographically to the formation of the mountain systems and establishment of the major biomes in Mesoamerica.
The diversification of Amazilia corresponds to vegetation shifts in combination with regional orogenesis. Intriguingly, the timing of the major diversification events and dispersal into South America pre-dates the completion of the Panamanian isthmus c. 4 Ma before present.