Abstract
- Populations of flying squirrels occupying oak and oak-pine forests of the Mesoamerican highlands represent the least studied and most poorly known members of the genus Glaucomys. Traditionally, these Mesoamerican populations have been considered to be southern disjuncts of the southern flying squirrel, G. volans, a species that is also widespread across the deciduous and mixed-deciduous forests of eastern North America. The small number of Mesoamerican flying squirrel museum specimens in existence has made discerning the systematic and biogeographic relationships of these populations a challenge. In an effort to clarify the systematic position and biogeographic history of the Mesoamerican flying squirrels, ancient DNA techniques were used to extract, amplify, and sequence a 571-bp segment of the mtDNA cytochrome b gene from 34 of museum specimens. These represented five of six recognized subspecies of Mesoamerican flying squirrels. Mesoamerican flying squirrel data was combined with homologous sequences from representative populations of Glaucomys from across the rest of North America. This combine data set was phylogenetically analyzed using likelihood and Bayesians approaches. Results of phylogenetic analyses indicate that Mesoamerican flying squirrels form a sister monophyletic group to populations of G. volans from eastern North America. Within Mesoamerica, there are two distinct mtDNA lineages of flying squirrels: one comprising of populations from the Sierra Madre Oriental, Oaxacan highlands and Sierra Madre de Chiapas, and one comprised of populations from the Sierra Madre del Sur. These phylogenetic relationships suggest that divergence of Mesoamerican populations from those in eastern North America preceded a series of subsequent divergence events within Mesoamerica.