A genetic analysis of avian personality traits: correlated, response to artificial selection.

Individuals in a range of species consistently differ in their behavior towards mild challenges, over age and time. Differences have been found for several personality traits in a range of species. In great tits these traits have a genetic basis and are phenotypically correlated. Estimates of genetic correlations are, however, fundamental to understanding the evolution of consistent individual differences in behavior. This study analyzed two selection experiments on two avian personality traits, early exploratory behavior and risk-taking behavior. The selection lines used were both started using wild great tits (Parus major) from two natural populations. Genetic correlations were calculated using the response and the correlated response to artificial selection. We found genetic correlations ranging from 0.51 to 0.66, based on individual values, and from 0.84 to 1.00 based on nest means. Genetic correlations can be due to pleiotropic effects or to linkage disequilibrium. The different behavioral traits might therefore have a common genetic basis, possibly constraining independent evolution of personality traits in natural populations. These results are discussed in relation to domain generality and domain specificity of personalities.