Dispersal and gene flow in a butterfly with home range behavior: Heliconius erato (Lepidoptera: Nymphalidae).

Heliconius butterflies have been found to have low rates of dispersal in previous mark-recapture studies, and this lack of movement is due home-range behavior. An experiment on Heliconius erato was designed to investigate movement from the site of pupal eclosion. It was found that most of the movement occurs before the first capture of an individual in a mark-recapture study. After incorporating this early movement, the dispersal parameter, σ, is estimated to be at least 296 m (±30 m jackknifed standard error), and the "neighborhood population size", N, is about 50-150 individuals. These estimates of σ and N are more than 2 and 5 times larger, respectively, than estimates based on standard mark-recapture data, though they are small compared with estimates from other butterfly species. Severe limitations of using dispersal experiments to estimate gene flow and neighborhood size are discussed. Genetic data from color pattern loci in hybrid zones and from electrophoresis suggest that, if anything, the estimates of σ and N that I have obtained are still too low. Genetic and dispersal data together show that kin selection is an unlikely mechanism for the evolution of warning color and other supposed altruisms in Heliconius, unless occasional genetic drift is also involved.