Text by Lisanna Schmidt
Genetic differences between regions are usually studied for individual species. However, many species can reproduce with each other. We studied whether gene flow between two closely related sedge species influences regional differences. Our molecular genetic data support considerable gene flow between the species. Still, we detected clear genetic differences between species and regions, and more pronounced regional differences for the less common one. Thus, gene flow between the species appeared too weak to neutralise differences between the regional genetic structure of our study species. We encourage further regional-differentiation studies in groups of cross-compatible species.
Citation: Schmidt, L., Fischer, M., & Oja, T. (2018). Two Closely Related Species Differ in their Regional Genetic Differentiation Despite Admixing. AoB PLANTS, DOI: 10.1093/aobpla/ply007. (link to full text)
Regional genetic differentiation within species is often addressed in evolutionary ecology and conservation biology. Here, we address regional differentiation in two closely related hybridizing taxa, the perennial sedges Carex flava and C. viridula and their hybrid C. x subviridula in 37 populations in the north and centre of their distribution range in Europe (Estonia, Lowland (< 1000m a.s.l.) and Highland Switzerland) using ten putative microsatellite loci. We ask whether regional differentiation was larger in the less common taxon C. viridula or whether, possibly due to hybridization, it was similar between taxa. Our results showed similar, low to moderate genetic diversity for the three studied taxa. In total, we found 12 regional species-specific alleles. AMOVA, STRUCTURE and Multidimensional Scaling Analysis showed regional structure in genetic variation, where intraspecific differentiation between regions was lower for C. flava (AMOVA: 6.84%) than for C. viridula (20.77%) or C. x subviridula (18.27%) populations. Hybrids differed from the parental taxa in the two regions where they occurred, i.e. in Estonia and Lowland Switzerland. We conclude that C. flava and C. viridula clearly differ from each other genetically, that there is pronounced regional differentiation, and that, despite hybridization, this regional differentiation is more pronounced in the less common taxon, C. viridula. We encourage future studies on hybridizing taxa to work with plant populations from more than one region.