Bluehead Sucker and the Complex Drainage History of the Upper Little Colorado River

Authors: Marlis R. Douglas, Whitney J.B. Anthonysamy, Mark A. Davis, Max R. Bangs, Glenn Selby, Jeff Cole, Michael E. Douglas

Year: 2013 (xlv)

Abstract

We generated mitochondrial (mt) and microsatellite (msat) DNA data for 340 Bluehead Sucker, Catostomus discobolus, collected from drainages of the Defiance Plateau, Chuska Mountains (Navajo Nation) and Zuni River (upper Little Colorado River, NM). These data were integrated within a range-wide DNA database of Bluehead Sucker to assess levels of gene flow and degree of isolation among populations, and to identify evolutionary (=ESUs) and management units (=MUs). Zuni River, Defiance Plateau and Chuska Mountain populations share a common mtDNA haplotype that falls within a previously recognized Colorado River ESU. Chuska Mountain harbors a second haplotype that also falls within the Colorado River ESU. Introgression by Rio Grande Sucker, Catostomus plebeius, was only detected in a single individual in the Zuni River (Rio Nutria). However, msat DNA indicated that Zuni River, Defiance Plateau and Chuska Mountain are distinct management units with no gene flow among these areas. Genotypes from the Rio Nutria reflect historic introgression with Rio Grande Sucker, but admixture was not detected elsewhere in the Zuni River. Genotypes that define Zuni River Bluehead Sucker are not found within the Defiance Plateau and Chuska Mountain drainages. In conclusion, Bluehead Sucker in northeastern AZ/ northwestern NM reflects a complex evolutionary history, with periods of isolation punctuated by drainage re-arrangements and potential stream captures. Distinct gene pools are found in drainages of the Chuska Mountains, the Defiance Plateau, the Zuni River, as well as the upper Little Colorado River.