26 March 2010: Thure Hauser

Frequencies and effects of hybridisation between two arctic plant species: Pyrola grandiflora and P. minor

Thure P. Hauser

dep. Agriculture & Ecology, Copenhagen University


In the Arctic, hybridization, polyploidisation and introgression have been important for the evolution of the flora. With the predicted and ongoing change of climate, there will be an increased influx of plants from warmer parts of Eurasia and America. The fate of these newcomers, and of the resident species, will depend on the competitive and reproductive interactions between them.

Two species of Pyrola (Danish: vintergrøn) grow in Greenland. Both have a circumpolar distribution, but P. minor has a more southern distribution including Europe. At Disko Island on the west coast, P. minor has its northern limit, and hybridizes with P. grandiflora. In a project financed by the Carlsberg Foundation, we study the dynamics of hybridization between the two species to evaluate how hybridization may affect their distributions locally and regionally. Last summer we collected material to test if hybridization has led to integration of genetic material of one species into the other (introgression) by characterizing the genetic and morphological composition of local populations of the species. To test how easy it is for the two species to hybridize, we further did controlled pollinations between the species and hybrids and evaluated to what extent seeds are produced. In the coming summer, we will survey how often plants are actually pollinated, how well foreign pollen grows in the styles, and how successful hybrids grows in the habitats of the parental species.

12 March 2010: Bodil Ehlers

Adapting to your chemical neighbor: Thyme and its associated plants

Bodil K Ehlers

Institute of Biology, University of Southern Denmark


It is well known that plant allolochemicals can have profound effects on associated species, and that plants with a history of co-existence with chemical neighbour plants perform better in their presence compared to naïve plants. This suggests that plant communities may indeed be quite co-evolved and that associated plants may locally adapt to the presence of a “chemical neighbor” plant.

The genus Thymus is known for its production of aromatic compounds, whose main constitution is terpenes – mainly monoterpenes. The thyme genus has a genetic polymorphism for the production of these terpenes both within and among species. These monoterpenes are known to differentially affect performance of herbivores, soil-microorganisms, and the germination and growth of other plants. We have studies how associated plant species perform under the influence of thyme monoterpenes, and found that a number of plant species show an adaptive response to growing with their “home” terpene. In a recent study we demonstrated that associated plants show genetic variation for the sensitivity to thyme monoterpenes, and that this variation is in accordance with selection operating, thus suggesting that the presence of thyme plants in a community can act as a selective agent on the genetic variation of associated plants. Moreover, we have evidence that the outcome of the interaction with thyme and associated plants is strongly affected by the presence of soil microorganisms. I will present these findings and future plans and discuss how biotic interaction and intra species genetic variation can affect community structure and evolution.