Karyotypic and Evolutionary Relationships of the Yellowstone (Salmo clarki bouvieri) and West-Slope (S. c. lewisi) Cutthroat Trout

Abstract

Yellowstone cutthroat trout (Salmo clarki bouvieri) have 64 chromosomes, without any subtelocentric chromosomes, while west-slope cutthroat trout (S. c. lewisi) have 66 chromosomes, including 12 subtelocentrics. Both subspecies have 104 chromosome arms. Chromosomal similarities are apparent between the Yellowstone cutthroat and Great Basin cutthroat subspecies, and between west-slope cutthroat trout and coastal cutthroat trout. These results demonstrate that at least two distinct evolutionary lines of cutthroat trout are present in the northern Rocky Mountain region. Key words: Salmo clarki, karyotypes, Yellowstone cutthroat trout, west-slope cutthroat trout, evolutionary relationships