Success factors of great oceanic dispersers: Case of Squamata in the Pacific Ocean

Abstract

AbstractThe Pacific Ocean is the largest in the world, and it contains many remote archipelagos, some of which are distant more than 4000 km from continents. Despite their isolation, these archipelagos harbour diverse assemblages of squamate reptiles (lizards and snakes), and these species differ greatly in their dispersal ranges. This study tested the hypothesis that there is a spatial effect on the variation among species in dispersal ability and that it is also associated with the evolutionary relationships among species and their life‐history strategies (body size and reproductive mode). The results indicated greater spatial than phylogenetic effects on the variables describing interspecific dispersal. The unisexual reproduction mode in squamates is not associated with a greater ability to colonize than sexual species that rely on similar mechanisms of dispersal. The higher reproductive rate of unisexual taxa might be initially advantageous for establishment on remote oceanic islands because of the unlikely arrival of sexual congenerics, which are frequently superior competitors in island ecosystems. Body size tends to exert a negative effect on the dispersal capacity of island squamates, but this relationship is positive in a subgroup of recently introduced commensal species.