Strong genetic exchange among populations of a specialist bee, <Emphasis Type="Italic">Andrena vaga</Emphasis> (Hymenoptera: Andrenidae) |
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Authors: | N Exeler A Kratochwil A Hochkirch |
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Institution: | (1) Department of Biology/Chemistry, Division of Ecology, University of Osnabrück, Barbarastr. 13, 49076 Osnabrück, Germany |
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Abstract: | Habitat fragmentation is believed to be a key threat to biodiversity, with habitat specialists being stronger affected than
generalists. However, pioneer species might be less affected by fragmentation, as their high colonization potential should
increase gene flow. Here, we present an analysis of the genetic structure of populations of the solitary bee Andrena vaga, which naturally occurs in sandy habitats and is specialized on willow (Salix) pollen as larval food and sandy soils as nesting sites. While the species is widespread in the young sandy landscapes of
our main study area (Emsland, northwestern Germany), it occurs less frequently in the Lower Rhine valley. Our analyses of
six polymorphic microsatellites show that the populations are only slightly differentiated, suggesting a relatively strong
gene flow. No genetic structure corresponding to the geographic origin was found as the variability within populations accounted
for the major proportion of variation. FST values were higher and allelic richness was lower in the Lower Rhine valley, supporting the hypothesis that habitat availability
affects the degree of genetic exchange between populations. Inbreeding coefficients were generally high and nearly all populations
had a heterozygote deficiency, which could be explained by the breeding strategy of A. vaga, which nests in aggregations. |
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Keywords: | Fragmentation Specialization Connectivity Isolation by distance Inbreeding |
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