Dispersal polymorphisms from natal phenotype-environment interactions have carry-over effects on lifetime reproductive success of a tropical parrot

We examined how interactions between an individual's phenotype and its environment affect natal dispersal at multiple scales and the effects on lifetime reproductive success using a 22-year study of green-rumped parrotlets (Forpus passerinus). Dispersal increased or decreased lifetime reproductive success depending upon an individual's natal environment and phenotype. Many of the phenotypic traits and environmental conditions that influenced lifetime reproductive success also influenced dispersal, such as clutch size and competition, and this differed with scale. By examining phenotype-environment interactions, we observed both positive and negative effects of rainfall, habitat quality and competition on dispersal depending upon phenotype. The dispersal behaviours of juveniles typically resulted in higher lifetime reproductive success. Thus, individuals commonly exhibit ideal free behaviour and results provide support for the occurrence and maintenance of dispersal polymorphisms. This study highlights the long-term, carry-over effects of natal environment, natal phenotype and dispersal tactic on lifetime reproductive success.