Dispersal and Recruitment in Streams: Evidence from Genetic Studies

Abstract

Analysis of genetic variation among populations of stream invertebrates provides a measure of the consequences of effective dispersal, and can be used to determine the extent of movement within and between streams and to infer the likely mechanisms involved. In our recent studies of rainforest stream invertebrates, we have found considerable genetic differentiation among populations of fully aquatic taxa, indicating limited in-stream movement on a very small scale. Adult flight appears to be the principal mechanism of dispersal for aquatic insects; however, analysis of the genetic structure of larval populations of some species also suggests that in-stream movement is limited to a small spatial scale, Furthermore, detailed analysis of the genetic structure of larval populations suggests that recruitment at the reach scale is the result of only a few adult matings and most likely from oviposition by only a few females. We propose that dispersal capability and the stochastic effects of recruitment are key determinants of observed spatial and temporal variation in community structure in some streams.

Macroinvertebrates and Excessive Fine Sediment Conditions in Oregon Coastal Streams

“…Stream invertebrates are generally poor fliers and can only migrate relatively short distances during their terrestrial stages. Analysis of genetic variation among stream invertebrate populations suggests that dispersal capability and reproductive strategy of adult invertebrates is a limiting factor in their ability to move across large spatial scales (Bunn and Hughes 1997).…”

High gene flow due to pelagic larval dispersal among South Pacific archipelagos in two amphidromous gastropods (Neritomorpha: Neritidae)

“…In contrast, fully lotic species are frequently genetically structured within watersheds or even within reaches (Bunn and Hughes, 1997;Marten et al, 2006). Lotic habitats are rare in the South Pacific, occurring only on volcanic islands that are tall enough to generate their own adiabatic rainfall.…”

Genetic contributions to the study of taxonomy, ecology, and evolution of mayflies (Ephemeroptera): review and future perspectives

“…The 'patchy recruitment hypothesis' (Schmidt et al 1995;Bunn and Hughes 1997) states that populations are founded by small number of females in each generation. This constitutes a bottleneck and leads to low heterozygosities.…”

“…Population genetics studies of mayflies (Ephemeroptera), here defined as publications that reported F selection favouring alleles at some loci in some cases, although this has not been explicitly tested for mayflies. But most of the reduction of heterozygosity in mayflies appears random, rather than at the same loci as might be expected if loci were under selection (Bunn and Hughes 1997). Parthenogenesis has been documented in a number of mayfly species (e.g.…”