Catostomus in México: Phylogenetic Investigations

Authors: Casey B. Dillman, Adria Pilsits, Richard L. Mayden

Year: 2009 (xli)

Abstract

The genus Catostomus is comprised of 25 described species. Eight of these species are known to occur in México, three of which are endemic. Since the description of C. cahita and C. leopoldi in 1986, representatives of Catostomus in México have received limited attention. Recent collection efforts in the Sierra Madre Occidental and surrounding areas of México have resulted in numerous samples of Catostomus. This sampling has also provided key observations that additional, and undescribed, morphological variation exists throughout the area. To add additional data to the morphological observations, a molecular phylogenetic investigation was undertaken. Three mitochondrial loci were used in this study, primarily because of homology issues in the nuclear DNA of tetraploid species. Results indicate that the genus Catostomus is not monophyletic, and species from México do not form a monophyletic group. Additionally, the inter-relationships within species, i.e. lineages, are complex. These results indicate a unique history for the fauna, one that has likely involved numerous cases of stream capture, as well as establish the need for future work inclusive of additional populations and use of independent nuclear loci.