Search

Understanding the mechanisms driving population divergence may be an important step in achieving conservation goals. Estimates of population divergence at neutral markers ( FST) can be compared with divergence at quantitative traits ( QST) to determine whether population differentiation is being driven by neutral processes such as genetic drift or by selection. We examined growth-related fitness traits, specifically length, weight, and condition factor, at various life history stages in coho salmon . Fish from two populations originating in different evolutionarily significant units and with different histories of selection were reared in a common environment, and weight and length measurements were collected for the alevin and juvenile stages during the first year of growth. Divergence at neutral markers was estimated from 10 microsatellite loci typed in each of the two populations ( FST = 0.089, 95% confidence interval = 0.056-0.0123). While QST tended to be greater than FST across all sample dates, this relationship was only significant when juvenile traits were combined for all sample dates ( QST = 0.406, 95% confidence interval = 0.305-0.468). These results suggest that diversifying selection is driving the differentiation between the two populations examined for the juvenile growth traits measured. [ABSTRACT FROM AUTHOR]