No Genetic Evidence for Hybridization Between Rio Grande Sucker, Catostomus Plebeius, and the Introduced White Sucker, Catostomus Commersoni, in the Rio Grande.

Hybridization with the introduced white sucker, Catostomus commerson, has been blamed in part for the decline of the Rio Grande sucker, C. plebeius, in the upper Rio Grande basin of Colorado and New Mexico but without convincing evidence. Here we report results from a genetic study of hybridization between the two species across their sympatric range in New Mexico. We used two nuclear microsatellite markers and one mitochondrial DNA marker to identify hybrids. These genetic methods detected no F1 or backcross hybrids in larvae, young-of-the-year or adults from the upper Rio Grande basin. This indicates that hybridization between the two species occurs rarely, if ever. [ABSTRACT FROM AUTHOR]