Spatial Distribution and Dispersal in a Population of Drosophila

Abstract

Spatial distribution in a D. engyochracea population in Kipuka Ki (Hawaii [USA]) is nonuniform. Density of flies was highest close to a known breeding site, and sex ratio was different in the 2 sides of the road that crossed Kipuka Ki. Females were more attracted to banana baits than males. Flies dispersed easily all over the experimental area. The road acted as a small barrier to dispersal, especially for males. Data suggested that females moved more freely than males, but the evidence was poor. Males did not seem to disperse farther and easier than females. Migration rates and population sizes were estimated using a modified Lincoln-Pearson mathematical model and fallowing several restrictive conditions. The study area was calculated to have an actual population size (N) of approximately 40,000 or about 5.4 flies/m2. The spatial distribution and dispersal of D. engyochracea had important implications in population parameters. Effective population size (Ne) was not much influenced by difference in sex numbers, but was probably influenced by the unequal distribution of sexes in the population area.