Current address: Institut des Sciences de la Mer (ISMER), Université du Québec à Rimouski, 310 Allée des UrsuLines, Rimouski QC, G5L 3A1, Canada.
Heterogeneity within the native range: population genetic analyses of sympatric invasive and noninvasive clades of the freshwater invading copepod Eurytemora affinis
Article first published online: 14 SEP 2007
© 2007 The Authors. Journal compilation © 2007 Blackwell Publishing Ltd
Volume 17, Issue 1, pages 415–430, January 2008
How to Cite
WINKLER, G., DODSON, J. J. and LEE, C. E. (2008), Heterogeneity within the native range: population genetic analyses of sympatric invasive and noninvasive clades of the freshwater invading copepod Eurytemora affinis. Molecular Ecology, 17: 415–430. doi: 10.1111/j.1365-294X.2007.03480.x
- Issue published online: 14 SEP 2007
- Article first published online: 14 SEP 2007
- Received 30 March 2007; revision accepted 26 June 2007
- biological invasion;
- demographic history;
- Great Lakes;
- source population;
- St Lawrence River drainage
Invasive species are often composed of highly differentiated populations or sibling species distributed across their native ranges. This study analysed patterns of distribution and the evolutionary and demographic histories of populations within the native range of the copepod species complex Eurytemora affinis. Genetic structure was analysed for samples from 17 locations from both the invaded and native ranges in the St Lawrence River drainage basin, using 652 base pairs of the mitochondrial cytochrome oxidase subunit I gene. This study revealed a high degree of heterogeneity in genetic structure and habitat type in the native range, as well as a bias in the sources of invasive populations. Two genetically distinct clades showed a pattern of niche partitioning within the St Lawrence basin. The noninvasive North Atlantic clade primarily occupied the central portion of the St Lawrence Middle Estuary, whereas the invasive Atlantic clade was more prevalent along the margins, in the upstream reaches of the estuary and downstream salt marshes. Habitat partitioning and genetic subdivision was also present within the Atlantic clade. The freshwater populations were genetically more proximate to the Atlantic clade populations in the estuary than to those in the salt marsh, suggesting the estuary as the source of the invasive populations. The freshwater invading populations showed evidence of a modest population bottleneck. Populations from both clades showed genetic signatures of demographic population expansions that preceded the timing of the last glacial maximum, supporting the St Lawrence as a secondary contact zone between the two clades. Additional analyses on physiological and evolutionary properties of populations in the native range, along with analysis of the selection regime within native habitats, might yield insights into the evolutionary potential to invade.