Heterozygosity and morphological variability of chum salmon (Oncorhynchus keta) in southern British Columbia.

Abstract

We compared variability in two meristic and six morphometric characters with heterozygosity within and among 27 populations of chum salmon (Oncorhynchus keta) in southern British Columbia. Among individuals, there was no relationship between levels of heterozygosity at 10 electrophoretic loci and degree of meristic or morphometric variation. Decreased morphological variance was not associated with increased heterozygosity. Morphological variance and heterozygosity did not change with age for chum salmon maturing at three to five years of age. Among populations of chum salmon, increased levels of average heterozygosity were not associated with decreased variance of morphometric or meristic characters. Our results do not support the hypothesis that more heterozygous individuals show less phenotypic variability than more homozygous ones due to a canalization of morphology during development. Genetic distances between pairs of chum salmon populations were significantly correlated with pairwise Mahalanobis distances derived from meristic, but not from morphometric characters. Chum salmon are morphometrically adapted to the natal stream environment, whereas biochemical and meristic characters in these populations may be less affected by local selective forces.