The impact of floral morphology on genetic differentiation in two closely related biennial plant species

The genetic diversity and structure of plant populations are determined by the interaction of gene flow, genetic drift and natural selection. These processes are to some extent dependent on the mating system of plants, which in turn is largely determined by floral morphology and in particular the level of herkogamy (spatial separation between anthers and stigma). In a recent study published in AoBP, Mertens et al. compare the genetic differentiation and structure of populations of two closely related Centaurium species that display a large variation in floral morphology across two geographic regions in Europe (mainland Europe and the UK).

Close up of the flower of Centaurium erythraea. Image credit: B. Cuber (distributed under a CC-BY-SA 3.0 license).

The populations of both species show opposite patterns of genetic differentiation and structure, and the patterns are reversed between the two regions. For both species, there is a strong link between these patterns and the differences in floral morphology observed in the sampled populations. Overall, these results indicate that variation in floral morphology has a profound impact on structuring of genetic diversity, with populations displaying low levels of herkogamy showing the strongest patterns of genetic structuring and the reverse pattern in populations showing high levels of herkogamy. More extensive studies on mating system functioning, pollen transfer and dispersal patterns would provide more detail on the effects of selfing and patterns of gene flow within and between populations on the spatial genetic structure in both species.

Researcher highlight

Arne Mertens graduated at KU Leuven with a degree in Biology in 2016. During his Master’s thesis, he studied the evolution of mating systems in a subfamily of the coffee family under supervision of Dr. Steven Janssens and professor Hans Jacquemyn. After graduating, he took extra classes for half a year before becoming a research assistant at the lab of Plant Conservation and Population Biology. Here, he studied the population genetics of two closely related Centaurium species. On March 19 2018, he started a PhD at the Department of Biosystems under supervision of professor Rony Swennen, gaining insight into the potential distribution and genetic diversity of wild banana species. Arne is an evolutionary plant ecologist with an interest in plant mating systems and species distribution patterns.

Reference List

Mertens, A., Brys, R., Schouppe, D., & Jacquemyn, H. (2018). The impact of floral morphology on genetic differentiation in two closely related biennial plant species. AoB PLANTS, 10(5). https://doi.org/10.1093/aobpla/ply051