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Three species of pocket mice (Chaetodipus artus , C. goldmani , and C. pernix) characterize the Sinaloan subregion of the Sonoran regional desert. They occur primarily in Sinaloan thornscrub and monsoon (dry deciduous) forest biotic communities, both of which have suffered from agricultural conversion. Sinaloan thornscrub occurs along the coastal plains of southern Sonora and Sinaloa, México, and grades into monsoon forest in the foothills of the Sierra Madre Occidental. We describe the geographical and ecological distributions of the 3 species of Chaetodipus , evaluate evolutionary relationships within each species based on mitochondrial DNA sequence data, and compare these to previously described phenetic, allozymic, and chromosomal variation. We elevate the subspecies of C. pernix to full species, delineate evolutionary units within C. goldmani and C. artus that we formally recognize as subspecies, and evaluate the conservation status of all 3 species of Chaetodipus. [ABSTRACT FROM AUTHOR]

Chaetodipus nelsoni occurs on rocky substrates across the Mexican Altiplano. We investigated phylogeographic diversity within the species using morphologic, karyotypic, and molecular data. Data from nuclear (AFLP) and mitochondrial DNA support three distinct genetic groups with minimal substructuring coincident with biogeographic barriers previously identified in the Chihuahuan Desert and drainage basins of the Altiplano. We examined the morphological and karyotypic data in light of the molecular data. The results support recognition of three species within the currently accepted widespread C. nelsoni : 1) C. nelsoni restricted to a distribution centered on the El Salado River Basin; 2) elevation of C. n. collis to species, with two subspecies: one centered on Trans-Pecos Texas, the other on the Mapimí Basin (new subspecies); and 3) recognition of a new species, C. durangae , centered on the Nazas Basin and upper Río Mezquital drainage. [ABSTRACT FROM AUTHOR]

We evaluated evolutionary relationships of taxa within silky pocket mice of the Perognathus fasciatus species group, composed of 3 species, P. fasciatus, P. flavescens, and P. apache. These species are distributed throughout the Great Plains, Wyoming Basin, Colorado Plateau, and northern Chihuahuan Desert biogeographic regions in North America. We tested a previously postulated hypothesis of Pleistocene species divergence and introgression by analyzing mitochondrial DNA (mtDNA) and amplified fragment length polymorphisms (AFLPs). Both mtDNA and AFLP data support several genetic lineages in the fasciatus species group that are geographically structured. Molecular clock estimates reject a Pleistocene speciation hypothesis in favor of a deeper, more complex evolutionary history of initial divergence in the Miocene followed by secondary diversification beginning in the middle Pliocene and progressing through the Pleistocene. Results support recognition of an additional species within the group. Temporal and spatial congruence between the mtDNA clades in the fasciatus species group and other codistributed species of Perognathus appear to support a hypothesis of concerted diversification throughout the Chihuahuan Desert, Colorado Plateau, and Great Plains. [ABSTRACT FROM AUTHOR]

We investigated the evolutionary history of a group of silky pocket mice (Heteromyidae: Perognathinae: Perognathus flavus species group) composed of the species P. flavus and P. merriami to determine patterns and postulate causes of geographical diversification across arid grasslands and intermontane basins in western North America. The region represents a topographically complex landscape with a Neogene history of dramatic geological and climatic transformations. Phylogenetic and dating analyses of mitochondrial DNA support an initial split among 4 major lineages during the late Miocene, and this hypothesis receives further support from analysis of a portion of the nuclear interphotoreceptor retinoid-binding protein (IRBP) gene. Two of these lineages have a restricted geographic distribution in the Chihuahuan Desert, and 2 have distributions ranging across large portions of the Chihuahuan Desert, Colorado Plateau, Great Plains, and Tamaulipan Plain. Within the 2 widespread lineages further geographical diversification likely was concentrated in the Pliocene, which coincided with the origin of several hypothesized geographic barriers. These results are consistent with models of allopatric divergence driven by pre-Pleistocene geological and climatic events, particularly the late-Miocene expansion of interior grasslands and Miocene-Pliocene evolution of Basin and Range geomorphology. Therefore, the biogeographic structure displayed in the flavus species group may be predictive for a range of sympatric taxa. [ABSTRACT FROM AUTHOR]