Geographic Variation among Pacific Northwest Populations of Longnose Dace, Rhinichthys cataractae

Relatively little morphological variation exists among populations of longnose dace from the Columbia River Basin. On the other hand, coastal populations from Chehalis River, Umpqua River (Rhinichthys evermanni) and Coos River exhibit considerable morphological divergence both from each other and from the Columbia stock. Differences shown by samples from the coastal streams suggest that these populations have combinations of characters not shared by other North American representatives.