Contrasting demographic history and population structure in Capsella rubella and Capsella grandiflora, two closely related species with different mating systems
2011 (English)In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 20, no 16, 3306-3320 p.Article in journal (Refereed) Published
Mating system and population history can both have large impacts on genetic diversity and population structure. Here, we use multilocus sequence data to investigate how these factors impact two closely related Brassicaceae species: the selfing Capsella rubella and the outcrossing C. grandiflora. To do this we have sequenced 16 loci in approximately 70 individuals from 7 populations of each species. Patterns of population structure differ strongly between the two species. In C. grandiflora we observe an isolation-by-distance pattern and identify three clearly delineated genetic groups. In C. rubella, where we estimate the selfing rate to 0.90-0.94, the pattern is less clear with some sampling populations forming separate genetic clusters while others are highly mixed. The two species also have highly divergent histories. In close agreement with previous studies, our analysis gives very strong support for a recent bottleneck (18,600 ya) in C. rubella, which most likely represents speciation from C. grandiflora. In C. grandiflora there is moderate support for the standard neutral model in 2 of 3 genetic clusters, while the third cluster shows evidence of weak expansion. It is clear that mating system has an impact on these two species, for example affecting the level of genetic variation, genetic structure and potentially also the size of the bottleneck in C. rubella. However, our results also clearly show that a combination of past and present processes, some of which are not affected by mating system, are needed to explain the differences between C. rubella and C. grandiflora.
Place, publisher, year, edition, pages
2011. Vol. 20, no 16, 3306-3320 p.
selfing, Brassicaceae, genetic structure, genetic diversity
IdentifiersURN: urn:nbn:se:uu:diva-136767DOI: 10.1111/j.1365-294X.2011.05189.xISI: 000293750000003OAI: oai:DiVA.org:uu-136767DiVA: diva2:377475