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BMC Evolutionary Biology

, 16:153

First Online: 29 July 2016Received: 15 July 2016Accepted: 18 July 2016DOI: 10.1186-s12862-016-0723-z

Cite this article as: Weiss, M. & Leese, F. BMC Evol Biol 2016 16: 153. doi:10.1186-s12862-016-0723-z

Abstract

BackgroundThe actual connectivity between populations of freshwater organisms is largely determined by species biology, but is also influenced by many area- and site-specific factors, such as water pollution and habitat fragmentation. Therefore, the prediction of effective gene flow, even for well-studied organisms, is difficult. The amphipod crustacean Gammarus fossarum is a key invertebrate in freshwater ecosystems and contains many cryptic species. One of these species is the broadly distributed G. fossarum clade 11 type B. In this study, we tested for factors driving the genetic structure of G. fossarum clade 11 in a human-impacted landscape at local and regional scales. To determine population structure, we analyzed the mitochondrial cytochrome c oxidase 1 CO1 gene of 2,086 specimens from 54 sampling sites and microsatellite loci of 420 of these specimens from ten sites.

ResultsWe detected strong overall genetic differentiation between populations at regional and local scales with both independent marker systems, often even within few kilometers. Interestingly, we observed only a weak correlation of genetic distances with geographic distances or catchment boundaries. Testing for factors explaining the observed population structure revealed, that it was mostly the colonization history, which has influenced the structure rather than any of the chosen environmental factors. Whereas the number of in-stream barriers did not explain population differentiation, the few large water reservoirs in the catchment likely act as dispersal barriers.

ConclusionsWe showed that populations of Gammarus fossarum clade 11 are strongly isolated even at local scales in the human-impacted region. The observed genetic structure was best explained by the effects of random genetic drift acting independently on isolated populations after historical colonization events. Genetic drift in isolated populations was probably further enhanced by anthropogenic impacts, as G. fossarum is sensitive to many anthropogenic stressors. These findings highlight the importance of small-scale genetic studies to determine barriers restricting gene flow to prevent further loss of genetic diversity and maintain intact freshwater ecosystems.

KeywordsRealized dispersal Environmental stressors Freshwater organism Gammarus fossarum Gene flow Genetic isolation Electronic supplementary materialThe online version of this article doi:10.1186-s12862-016-0723-z contains supplementary material, which is available to authorized users.

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Autor: Martina Weiss - Florian Leese

Fuente: https://link.springer.com/







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