Behavioral variation shows heritability in juvenile brown trout Salmo trutta

Animal personalities (sometimes referred also as coping styles) and their fitness consequences are currently among the most intensively explored subjects in behavioral ecology. To estimate the evolvability and adaptability of individually consistent behavioral variation, there is a crucial need to quantify the genetics underlying personality. Here, we experimentally studied the repeatability of various individual behaviors and then estimated heritability of formed boldness, exploration, and aggression components in juvenile brown trout Salmo trutta in standardized laboratory environment. Principal component analysis indicated that individually recorded behaviors were described by two personality axes: the first reflecting boldness, exploration, and aggression and the second tendency to freeze. These personality components, as well as the originally recorded behaviors, were statistically significantly repeatable over time. The latter PC, but not the first one, was statistically significantly heritable, though at low level (h (2) = 0.142 +/- 0.096). These results suggest that additive genetic variation underlies phenotypically consistent behavioral patterns, proposing that any selection acting on behavior, stress tolerance, or correlated traits has a potential to induce evolution in fish personality.