Using genetic diversity to inform conservation efforts for native Cutthroat Trout of the Southern Rocky Mountains

Using genetic diversity to inform conservation efforts for native Cutthroat Trout of the Southern Rocky Mountains

Recent research on native Cutthroat Trout Oncorhynchus clarkii of the southern Rocky Mountains suggests a convoluted taxonomy confused by stocking in the early 1900s that obscured the native distributions of these fish.  DNA recovered from the few museum specimens collected 150 years ago shed light on the historical diversity and native ranges of lineages in Colorado. This study aims to characterize what remains of that diversity across the entire southern Rockies using a stratified random sampling design across the range of putative Colorado River Cutthroat Trout O. c. pleuriticus, Greenback Cutthroat Trout O. c. stomias, and Rio Grande Cutthroat Trout O. c. virginalis. Twenty-four biologists from four states collected 801 fish from 49 randomly selected conservation populations across Colorado, New Mexico, Utah, and Wyoming. Whole specimens were used to explore phenotypic differences in lineages suggested by molecular studies. Here, we used tissue samples collected prior to specimen preservation to describe mitochondrial haplotype diversity. These diversity patterns are critical to inform managers tasked with listing decisions for rare Cutthroat Trout lineages. Consistent with previous studies, four distinct lineages were recovered from sequence data on 648 base pairs of the ND2 mitochondrial gene. Substantial diversity was recovered in Rio Grande Cutthroat Trout (12 haplotypes), while only a single haplotype could be found in native Cutthroat Trout of the South Platte River basin. Within Colorado River Cutthroat Trout, nine haplotypes were recovered from 14 populations putatively native to the Upper Colorado, Gunnison, and Dolores basins (Green Lineage), but only six were found in 21 populations native to the Lower Colorado, Green, and Yampa basins (Blue Lineage). This was unexpected given the broad range of the Blue Lineage, and may suggest more recent ancestry of Green River basin fish. Rare haplotypes may indicate pockets of historical diversity. To avoid inadvertently “throwing away the pieces”, these conservation populations should be targeted for replication and protection to ensure their continued persistence.

Rogers, Kevin B.

Bestgen, Kevin R.

Epp, Janet

Native Cutthroat Trout

Southern Rocky Mountains

Genetics

11 pages

2014-09

Article

application/pdf

English

Wild trout symposium XI—looking ack and moving forward