Research Genetic signatures of long-term evolutionary history in a herbaceous, high-polyploid, clonal plant species in Central Europe

Genetic diversity is associated with sexual reproduction and is a driver of plant adaptation and diversification. However, there are also successful but almost exclusively vegetatively reproducing species. Among them is the enigmatic Eurasian herbaceous woodland species Cardamine bulbifera. Since the Last Glacial Maximum the species has expanded as an understorey woodland plant in Europe since c. 12,000 years ago via asexual propagation of vegetative (hence clonal) structures. The dodecaploid species stems from the gene pool of diploid sister species C. bipinnata and C. abchasica from the Caucasus region. While exploring the entire European distribution range we identified a genetically very diverse population in north-eastern Austria - the unglaciated Thaya Valley - lacking signatures of contemporary gene flow, in which genetic variation most likely stems almost exclusively from ancestral populations. We explored the hypothesis that the genetic diversity observed is a remnant of past reticulate rather than contemporary gene flow and that genotypes show strong environmental adaption to certain woodland types.  

The study shows that micro-scale distribution patterns of genotypes follow woodland types and ecological clines and indicate differences in the adaptive potential of identified and vegetatively dispersed plants. The studied meta population exhibits considerable genetic variation from past reticulate processes and provides compelling evidence for the hypothesis that past genetic variation has been preserved in this polyploid woodland species.