Molecular phylogenetics of theHandleyomys chapmanicomplex in Mesoamerica

Abstract

Handleyomys chapmani (Chapman’s Handley’s mouse) is a Mexican endemic rodent inhabiting humid montane forest of the Sierra Madre Oriental (SMO), the Oaxacan Highlands (OH), and the Sierra Madre del Sur (SMS). The systematic status of populations currently classified as H. chapmani has been problematic and to date evolutionary relationships among populations remain unresolved. In this study we use sequences from the mitochondrial cytochrome-b gene (1,143 base pairs [bp]) and intron 7 of the beta fibrinogen gene (621 bp) to reconstruct a phylogeny, estimate divergence times, and assess patterns of sequence variation over geography among samples of H. chapmani. This species was recovered as 2 monophyletic clades corresponding to the SMO-OH and SMS mountain ranges. Moreover, H. saturatior, the purported sister taxon to H. chapmani, was consistently recovered as the sister lineage to the SMO-OH clade, rendering H. chapmani paraphyletic. The geographic distribution of the 2 H. chapmani clades and of H. saturatior strongly correlate with the geographic extent of the SMO-OH, SMS, and the Trans-Isthmian Highlands (highlands east of the Isthmus of Tehuantepec through Central America) mountain ranges. Divergence times associate their isolation to late Pleistocene climatic