GENE FLOW AMONG CONSPECIFIC POPULATIONS OF BAETIS SP (EPHEMEROPTERA) - ADULT FLIGHT AND LARVAL DRIFT

The genetic structure of populations of Baetis sp. (Ephemeroptera:Baetidae) was used to draw inferences about the means of dispersal within and between stream systems of the Conondale Range, Queensland, Australia. Allozyme electrophoresis was used to examine allelic frequencies at five variable loci in geographically distant populations of nymphs in the same drainage and in nearby populations in different drainages. The results showed widespread gene now between drainages and a tendency for local differentiation. We concluded that adult night represents an effective means for dispersal between drainage systems. The differentiation between populations at a local scale and erratic deviations from Hardy Weinberg equilibrium could have occurred if the nymphs collected from any stream were the offspring of only a few adults. If this is the case, the dispersal capabilities of nymphs by swimming, crawling or drift may be minimal even within a single stream.