Morphological and genetic divergence of intralacustrine stickleback morphs in Iceland: a case for selective differentiation?
Version of Record online: 2 OCT 2006
Journal of Evolutionary Biology
Volume 20, Issue 2, pages 603–616, March 2007
How to Cite
ÓLAFSDÓTTIR, G. Á., SNORRASON, S. S. and RITCHIE, M. G. (2007), Morphological and genetic divergence of intralacustrine stickleback morphs in Iceland: a case for selective differentiation?. Journal of Evolutionary Biology, 20: 603–616. doi: 10.1111/j.1420-9101.2006.01250.x
- Issue online: 2 OCT 2006
- Version of Record online: 2 OCT 2006
- Received 9 May 2006; revised 29 August 2006; accepted 29 August 2006
- ecological speciation;
- habitat isolation;
- local adaptation;
- population structure;
- reproductive barrier;
The evolutionary processes involved in population divergence and local adaptation are poorly understood. Theory predicts that divergence of adjacent populations is possible but depends on several factors including gene flow, divergent selection, population size and the number of genes involved in divergence and their distribution on the genome. We analyse variation in neutral markers, markers linked to putative quantitative trait loci and morphological traits in a recent (< 10 000 years) zone of primary divergence between stickleback morphs in Lake Thingvallavatn, Iceland. Environmental factors, especially predation, are clearly implicated in reducing gene flow between morphs. There is continuous morphological and genetic variation between habitats with a zone centre similar to secondary contact zones. Individual microsatellite loci are implicated as being linked to adaptive variation by direct tests as well as by differences in cline shape. Patterns of linkage disequilibria indicate that the morphs have diverged at several loci. This divergence shows parallels and differences with the well-studied limnetic–benthic stickleback morphs, both in phenotypic divergence and at the genomic level.