Jm. Hughes et al., DISPERSAL AND RECRUITMENT OF TASIAGMA-CILIATA (TRICHOPTERA, TASIMIIDAE) IN RAIN-FOREST STREAMS, SOUTH-EASTERN AUSTRALIA, Freshwater Biology, 39(1), 1998, pp. 117-127
1. This study examined genetic variation within and among populations
of the caddis fly Tasiagma ciliata (Tasimiidae: Trichoptera) from rain
forest streams in south-east Queensland, Australia. 2. Very low levels
of genetic differentiation at large spatial scales, between subcatchm
ents and between catchments, indicated that dispersal by the winged ad
ults is widespread. However, significant genetic differentiation at th
e smallest spatial scale examined, within reaches in a single stream,
suggested limited movement by larvae within streams. 3. A patchy distr
ibution of deviations from Hardy-Weinberg equilibrium and differences
in patterns among allozyme loci suggested that populations in particul
ar reaches were the result of only a few matings. 4. These results are
surprising, given the large numbers of larvae present within a single
reach. We suggest that stochastic effects of recruitment may underlie
much of the spatial and temporal variation in population numbers in t
hese rainforest streams.