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Stable levels of gene diversity despite low effective population size in isolated perch and roach populations
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Animal Ecology.
(English)Manuscript (preprint) (Refereed)
Keyword [en]
temporal variation, effective population size, genetic diversity, isolation by time, perch, roach
URN: urn:nbn:se:uu:diva-108615OAI: oai:DiVA.org:uu-108615DiVA: diva2:236620
Available from: 2009-10-06 Created: 2009-09-24 Last updated: 2010-01-14Bibliographically approved
In thesis
1. Biodiversity in Swedish Cyprinid Fish: Insights Into Processes of Divergence
Open this publication in new window or tab >>Biodiversity in Swedish Cyprinid Fish: Insights Into Processes of Divergence
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Uncovering and understanding the processes that have led to the biological diversity we observe today are of fundamental interest in biology. Since direct observation of speciation is usually impossible, knowledge about the processes behind species formation can be gathered by studying mutations, natural/sexual selection, and genetic drift. In this thesis I aim to identify evolutionary processes that cause species divergence and, ultimately, speciation using Swedish cyprinid fish as a model system. Assuming that the demographic history of a population is mirrored in the genome, I studied the effects of a bottleneck on genetic variability in populations of roach. As expected, I found that a decrease in population size caused a decrease in genetic variability, a pattern that was obtained from both microsatellite and mitochondrial data. The importance of hybridization for speciation is debated, however, by analyzing morphology and microsatellites I could show that common bream and white bream and their interspecific hybrids are phenotypically and genetically differentiated and that ongoing geneflow is mainly unidirectional. Ongoing geneflow antagonizes the effect of genetic drift, but by studying isolated populations (= no gene flow) the impact of genetic drift can be assessed. Long-term isolated populations of roach and perch surprisingly showed stable levels of genetic diversity over time despite decreasing effective population size. However, each population genetically diverged during the period of investigation, a finding that is consistent with the effect of drift. An analysis of the systematic relationship of the 18 species of Swedish cyprinids revealed low congruence of phylogenies based on two different genetic markers. The position of the tench remains unresolved and the relationship of common bream and white bream as sister species cannot be confirmed. Within cyprinid fishes, diversification rates reveal a slowdown with time, a pattern that I found also in other fish clades and that is consistent with density-dependent cladogenesis. Overall, based on the findings presented in this thesis I emphasize that the maintenance of genetic variation in populations is essential since genetic variation is the key element for processes of divergence to act upon.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 35 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 677
speciation, hybridization, bottleneck, genetic drift, phylogeny, speciation rates, common bream, white bream, roach, Swedish cyprinid fish, Cyprinidae
National Category
Biological Sciences
urn:nbn:se:uu:diva-108969 (URN)978-91-554-7621-2 (ISBN)
Public defence
2009-11-20, Zootissalen, Villavägen 9, Uppsala, 10:00 (English)
Available from: 2009-10-29 Created: 2009-10-06 Last updated: 2009-10-29Bibliographically approved

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