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Parallelism and historical contingency during rapid ecotype divergence in an isopod

  • Fabrice Eroukhmanoff
  • A. Hargeby
  • N. N. Arnberg
  • O. Hellgren
  • Staffan Bensch
  • Erik Svensson
Publishing year: 2009
Language: English
Pages: 1098-1110
Publication/Series: Journal of Evolutionary Biology
Volume: 22
Issue: 5
Document type: Journal article
Publisher: John Wiley & Sons

Abstract english

Recent studies on parallel evolution have focused on the relative role of selection and historical contingency during adaptive divergence. Here, we study geographically separate and genetically independent lake populations of a freshwater isopod (Asellus aquaticus) in southern Sweden. In two of these lakes, a novel habitat was rapidly colonized by isopods from a source habitat. Rapid phenotypic changes in pigmentation, size and sexual behaviour have occurred, presumably in response to different predatory regimes. We partitioned the phenotypic variation arising from habitat ('selection': 81-94%), lake ('history': 0.1-6%) and lake x habitat interaction ('unique diversification': 0.4-13%) for several traits. There was a limited role for historical contingency but a strong signature of selection. We also found higher phenotypic variation in the source populations. Phenotype sorting during colonization and strong divergent selection might have contributed to these rapid changes. Consequently, phenotypic divergence was only weakly influenced by historical contingency.


  • Biological Sciences
  • pigmentation
  • historical contingency
  • adaptive radiation
  • mating propensity
  • evolution
  • parallel
  • phenotype sorting


  • Molecular Ecology and Evolution Lab
  • ISSN: 1420-9101
E-mail: erik [dot] svensson [at] biol [dot] lu [dot] se


Evolutionary ecology

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Centre for Animal Movement Research
Evolutionary Ecology, Department of Biology
Ecology building S-223 62 Lund Sweden