Population regulation by dispersal under selection pressure for and against dispersal: an experimental test with beetles, Tribolium confusum
نویسنده
چکیده
Hypothesis: Dispersal outside a local population maintains population density below the possible maximum, but within a single local population selection acts against dispersal and consequently against such maintenance. Individuals that disperse exhibit lower fitness that is correlated with their smaller body size. Organism: Laboratory populations of Tribolium confusum beetles. Methods: Four confined populations with no dispersal, four with the progeny of dispersing individuals removed and four with the progeny of non-dispersing individuals removed were maintained and monitored for seven generations. Results: Confined populations were larger than those from which dispersal was allowed. From generation three onwards, dispersal rates were significantly lower in the population in which progeny of dispersing beetles were removed than in the population in which progeny of non-dispersing beetles were removed. The differences in dispersal rates mentioned above affected population density in the native populations but not in the places to which beetles emigrated. The removal of the progeny of dispersing individuals does not eradicate dispersal altogether. Average body weights of dispersing beetles are not lower than of those of nondispersing beetles.
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