Enzyme Heterozygosity and Fecundity in a Naturalized Population of Brook Trout (Salvelinus fontinalis)

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Abstract
Relationships between heterozygosity at 7 enzyme loci and components of fecundity as well as female size were examined in a naturalized population of brook trout, Salvelinus fontinalis, from Algonquin Park, Ontario. A significant positive regression between the number of heterozygous loci per fish and estimated egg number per female was detected. Multilocus heterozygosity (summing heterozygosity across all loci) was positively associated with total ovulated egg weight. When adjustments were made for female weight, multilocus heterozygosity did not explain a significant amount of variation in either total ovulated egg weight or other components of fecundity. A marginally significant (P = 0.055) linear relationship existed between multilocus heterozygosity and female weight but not length. Treating each locus separately rather than summing heterozygosity across all loci improved the predictive value of heterozygosity on estimated egg number per female, female weight, and length. Individuals heterozygous at Aat-1,2 had more eggs than homozygotes whereas heterozygotes at G3p-1, were heavier or longer than homozygotes.