VARIATION IN ADULT LIFE-HISTORY AND MORPHOLOGY AMONG LAKE WASHINGTON SOCKEYE-SALMON (ONCORHYNCHUS-NERKA) POPULATIONS IN RELATION TO HABITATFEATURES AND ANCESTRAL AFFINITIES

Body size, age composition, and male body depth were compared among fi ve Lake Washington sockeye salmon (Oncorhynchus nerka) populations. Tw o of the populations (Bear and Cottage creeks) were indigenous to the watershed and three (Cedar River, Issaquah Creek, and Pleasure Point) were non-native (from Baker Lake, Washington). To isolate the relative contributions of habitat type and ancestral relatedness to phenotypic variation, we compared populations with (i) the same origin and simil ar habitats, (ii) different origins and different habitats, (iii) the same origin and different habitats, and (iv) different origins and sim ilar habitats. Spawning salmon in the Cedar River were older and large r than those in the native populations, a result consistent with their origin (contemporary Baker Lake fish were also large and old) and wit h habitat variation (the Cedar River is much larger than Bear and Cott age creeks). Body size and age composition did not differ among the th ree non-native populations, but the body depth of males spawning on th e lake beach (Pleasure Point) was greater than that of males in the Ce dar River, suggesting adaptive divergence. Adaptive convergence may al so have occurred because the population in Issaquah Creek (intermediat e-sized creek) did not differ appreciably from those in Bear and Cotta ge creeks.