Genetic contribution of native and introduced catostomids to larval drift in experimental and control streams of the Gunnison River basin in Colorado

Authors: Schwemm, Michael R.*, Thompson, Kevin, Turner, Thomas, Carson, Evan W.

Year: 2015 (xlvii)

Abstract

Diagnostic microsatellite markers were used to characterize interspecific hybridization among native and non-native catostomids in two streams of the Gunnison River system. As part of an experimental study to evaluate the influence of non-native removal on hybridization, we conducted a baseline genetic assessment of catostomid larvae at two geographically proximate streams, Potter and Cottonwood creeks, one of which (Cottonwood) will be subject to removal of non-native suckers (via fish trap) and their hybrids prior to spring spawning in 2016. Baseline admixture analyses revealed that streams differed in species composition and levels of interspecific hybridization. Genetic characterization showed that the prospective treatment stream (Cottonwood) was composed primarily of non-native white sucker (Catostomus commersonii), native flannelmouth sucker (Catostomus latipinnis), and advanced backcrosses to flannelmouth between these species. In contrast, larval drift in the proposed control stream contained primarily native flannelmouth or native bluehead suckers (Catostomus discobolus), with relatively few hybrids (advanced backcrosses) between these species. These results provide a baseline of the level of hybridization among species prior to non-native removal, and additionally offer insight into the incidence of natural hybridization between flannelmouth and bluehead suckers.