Risky dispersal: avoiding kin competition despite uncertainty.

Leaving a population without having information about the surrounding areas is highly risky. Candidates for dispersal may reduce these risks by making decisions based on the level of connectivity between patches, e.g., through immigrants. The benefits of information acquisition may vary within a population according to the dispersal cause and the phenotype of the candidate disperser. For instance, kin-based dispersers should be prepared to accept higher dispersal cost than individuals leaving for competition with congeners, and individuals of better condition should better deal with the costs of dispersing. We investigated whether the use of information obtained from immigrants depended on the reason for dispersal and the phenotype of individuals in common lizards (Lacerta vivipara). Dispersal decisions with respect to connection status depended on the cause of dispersal and on body mass. When intraspecific competition was the driving force behind dispersal, the information carried by immigrants allowed candidate dispersers to decrease uncertainty about the success of dispersal. Therefore, larger individuals dispersed when connectivity was low, whereas smaller individuals dispersed when connectivity was high. When kin competition dominated, dispersers did not adjust their dispersal decisions on the basis of information about the existence of surrounding populations, and larger individuals dispersed whatever the connectivity. These results provide support for the hypothesis that kin competition is one of the factors driving colonization.