9423146 DOUGLAS Large-scale geographic changes have occurred in western North America as a result of geologic upheaval and climate. These have spatially isolated western fishes to produce patterns of geographic variation within and between lineages. Congruence between pattern and process will be tested by using as a model organism a morphologically variable, widespread, western minnow (Rhinichthys osculus). Forty-five populations (50 individuals each) will be sampled from 10 different river systems (which form five different basins, each with known geological histories). Four other species will be used as comparisons for analyses. Seven individuals per population will be evaluated for genetic diversity by evaluating the DNA of their respective cellular mitochondria. Data will be evaluated using (a) traditional population genetic and geographic variation techniques, and (b) newer techniques which evaluate ancestor-descendant relationships among populations. Results from this study will provide a generalized model of geographic affinity between populations of a widely distributed fish species in western North America. This model can then be evaluated for congruence with other widespread (but less easily sampled) species of western fishes.
