The importance of a good neighborhood: dispersal decisions in juvenile common lizards are based on social environment

Within a population, dispersers are likely to differ in their motivation and adaptations to disperse; yet individual heterogeneity in dispersal decisions is still poorly documented. In the common lizard, females can be classified into 3 types of ventral color (yellow, orange, and mixed) that signal alternative strategies in reproduction and behavior. The reproductive success of these alternative strategies depends on the frequency of each color type in their local environment. Therefore, we predicted that adaptive emigration and settlement decisions should differ between color types and respond to the social composition of the environment. To test this prediction, we analyzed juvenile local dispersal decisions in response to an experimental manipulation of the local color type frequencies. Offspring from orange or mixed females showed decreased dispersal rate in populations where the frequency of yellow females was increased, and those who dispersed chose to settle in environments with lower female density but higher frequency of yellow females. Our results demonstrate that the composition of the social environment is used as a direct cue for dispersal decisions that provides information on resource competition and environment quality. The frequency of female color types is thus a key parameter of the social environment that influences habitat choice decisions. However, the pattern of spatial autocorrelation of adult females was not consistent with these color-related dispersal patterns, which suggest that other processes also participate in shaping the distribution of individuals at the population scale.