Multigenerational hybridisation and its consequences for maternal effects in Atlantic salmon

Outbreeding between segregating populations can be important from an evolutionary, conservation, and economical- agricultural perspective. Whether and how outbreeding influences maternal effects in wild populations has rarely been studied, despite both the prominent maternal influence on early offspring survival and the known presence of fitness effects resulting from outbreeding in many taxa. We studied several traits during the yolk-feeding stage in multigenerational crosses between a wild and a domesticated Atlantic salmon (Salmo salar) population up to their third-generation hybrid in a common laboratory environment. Using cross-means analysis, we inferred that maternal additive outbreeding effects underlie most offspring traits, but that yolk mass also underlies maternal dominant effects. As a consequence of the interplay between additive and dominant maternally controlled traits, offspring from first-generation hybrid mothers expressed an excessive proportion of residual yolk mass...