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Anthropogenic Habitats (anthropogenic + habitat)
Selected AbstractsFlexible social organization and high incidence of drifting in the sweat bee, Halictus scabiosaeMOLECULAR ECOLOGY, Issue 8 2009YUKO ULRICH Abstract The very diverse social systems of sweat bees make them interesting models to study social evolution. Here we focus on the dispersal behaviour and social organization of Halictus scabiosae, a common yet poorly known species of Europe. By combining field observations and genetic data, we show that females have multiple reproductive strategies, which generates a large diversity in the social structure of nests. A detailed microsatellite analysis of 60 nests revealed that 55% of the nests contained the offspring of a single female, whereas the rest had more complex social structures, with three clear cases of multiple females reproducing in the same nest and frequent occurrence of unrelated individuals. Drifting among nests was surprisingly common, as 16% of the 122 nests in the overall sample and 44% of the nests with complex social structure contained females that had genotypes consistent with being full-sisters of females sampled in other nests of the population. Drifters originated from nests with an above-average productivity and were unrelated to their nestmates, suggesting that drifting might be a strategy to avoid competition among related females. The sex-specific comparison of genetic differentiation indicated that dispersal was male-biased, which would reinforce local resource competition among females. The pattern of genetic differentiation among populations was consistent with a dynamic process of patch colonization and extinction, as expected from the unstable, anthropogenic habitat of this species. Overall, our data show that H. scabiosae varies greatly in dispersal behaviour and social organization. The surprisingly high frequency of drifters echoes recent findings in wasps and bees, calling for further investigation of the adaptive basis of drifting in the social insects. [source] Understanding the biodiversity consequences of habitat change: the value of secondary and plantation forests for neotropical dung beetlesJOURNAL OF APPLIED ECOLOGY, Issue 3 2008Toby A. Gardner Summary 1Secondary and plantation forests are becoming increasingly widespread in the tropics. A recent meta-analysis on the impacts of land-use change on tropical forest dung beetles concluded that regenerating forests can be effective in helping to offset species loss following deforestation. However, our understanding of the extent to which these results can be generalized to new locations remains very poor. 2We attempted to overcome many of the design limitations that characterize previous studies by collecting spatially independent dung beetle samples from primary, secondary and Eucalyptus plantation forests in north-east Brazilian Amazonia across a large quasi-experimental landscape that minimized confounding edge and fragmentation effects. 3We recorded 9203 dung beetles, comprising 85 species. Species richness was significantly higher in primary forest and the majority of species were more abundant there than elsewhere, whereas secondary and plantation sites harboured an impoverished subset of primary forest species. 4Our data illustrate the low value of tropical secondary and plantation forests for dung beetles in our study area, and our conclusions are more pessimistic than those of earlier studies. 5Because of differences in the order of species rank-abundance and rank-biomass patterns, re-coding community data from abundance to biomass significantly altered the analytical weight of individual species in determining community patterns. Larger bodied beetles were more prone to local extinctions and abundance declines and this effect was consistent both within and between genera. 6Synthesis and applications. Our study demonstrates that secondary and plantation forests in a large neotropical landscape host exceptionally impoverished dung beetle communities. Furthermore, the depletion of beetle abundance combined with a reduction in average body mass in converted forests is likely to have detrimental consequences for the maintenance of dung beetle-mediated ecosystem services in these habitats. Differences in biogeographical and landscape context, and the influence of common limitations in sampling design, may explain why many other studies have painted a more optimistic picture of the conservation value of anthropogenic habitats. In the absence of further evidence we caution strongly against the claim that forest regeneration schemes on degraded land can effectively offset the loss of species following deforestation, and urge that conservation strategies prioritize the protection of remaining areas of primary forest. [source] What is the origin of the carabid beetle fauna of dry, anthropogenic habitats in western Europe?JOURNAL OF BIOGEOGRAPHY, Issue 4 2000Johan Andersen Abstract Aim To study the origin of the carabid beetle fauna of dry, open anthropogenic habitats. Location Various parts of Europe. Methods Collecting by hand in habitats influenced by humans (arable land, sand pits, ruderal places, road verges, meadows) and naturally open habitats such as talus, supralittoral sand dunes, alvar as well as littoral habitats in south and central Scandinavia. Studies made in other parts of Europe were included in the discussion. Results and conclusion The material comprises about 37,700 specimens. About 8% of the Scandinavian species occurring in anthropogenic habitats may have a littoral origin, about 10% may originate from forests whereas about 9% are euryoecious. A majority of the species (about 66%) originate from primarily open, dry habitats and many of them constitute a steppe or steppe-like element. They invaded the bare landscape soon after the deglaciation and probably survived in naturally open habitats (supralittoral sand dunes, talus, alvar, old riverbeds) during the postglacial warm period, but some species have a recent origin in Scandinavia. [source] | ||||||||||