Individual heterozygosity and survival in wild

My project aims at revealing the relationship between individual genetic variation and survival which is a basic question of population genetics. The predator avoidance skills of juvenile Atlantic salmon (Salmo salar) with different levels of genetic heterozygosity (H) will be studied. The project includes behavioural observations in aquaria, genetic analyses, and survival data from the wild. Using extensive release-recapture experiments in semi- natural and wild habitats my study will test the currently prevailing views of the heterozygote advantage that are based on studying merely the association of H and select fitness traits. I will study changes in salmon heterozygosity mainly as a result of selection by their predators. I will use a combination of supposedly neutral markers like microsatellites, and functional markers (SNPs in coding genes and MHC genes) that can be under balancing selection. This enables me to control for changes in H due to genetic drift at release-recapture trials. Nearly all fieldwork (data collection) was completed in autumn 2006 and the current proposal aims at receiving financing for the laboratory work and subsequent data analyses and manuscript preparation. The main questions addressed in the study are: (1) Does H predict survival in the wild? (2) Is the survival of individuals with different level of H mediated through differences in their antipredator behaviour? (3) Can learning of predator threat mask the genetic effect on predator avoidance skills, or is H correlated with individual`s learning ability? (5) Can the strength of innate predator avoidance response be explained with individual differences in the expression levels of salmon odorant receptor (OR) genes? Partly owing to practical inconveniencies, all previous investigations about heterozygosity-fitness correlations (HFCs) have either been conducted in the laboratory or have measured only select fitness correlates and not actual survival. Predation on juvenile stage is, however, a major mortality factor and can determine the recruitment success of individuals of many species. Based on existing evidence about behavioural correlations, I suggest that while salmonid fish of higher microsatellite H can be more vigorous and possess increased competitive ability in captivity, once released among predators, could suffer increased mortality due to their bold personality. I thus expect individuals with intermediate levels of H to gain survival advantage under strong predation pressure in the wild.