Personality-matching habitat choice, rather than behavioural plasticity, is a likely driver of a phenotype‒environment covariance

Abstract

An emerging hypothesis of animal personality posits that animals choose the habitat that best fits their personality, and that the match between habitat and personality can facilitate population differentiation, and eventually speciation. However, behavioural plasticity and the adjustment of behaviours to new environments have been a classical explanation for such matching patterns. Using a population of dunnocks (Prunella modularis), we empirically tested whether personality or behavioural plasticity is responsible for the nonrandom distribution of shy and bold individuals in a heterogeneous environment. We found evidence for bold individuals settling in areas with high human disturbance, but also that birds became bolder with increasing age. Importantly, personality primarily determines the distribution of individuals, and behavioural adjustment over time contributes very little to the observed patterns. We cannot, however, exclude a possibility of very early behavioural plasticity (a type of developmental plasticity) shaping whatwe refer to as ‘personality’. Nonetheless, our findings highlight the role personality plays in shaping population structure, lending support to the theory of personalitymediated speciation. Moreover, personality-matching habitat choice has important implications for population management and conservation.