The role of local adaptation in the relationship between an endangered root hemiparasite Euphrasia rostkoviana, and its host, Agrostis capillaris

Abstract

We experimentally studied the role of local adaptation and the co‐evolutionary relationship between an annual, endangered root hemiparasiteEuphrasia rostkovianaand its main hostAgrostis capillaris.According to our hypothesis, the existence of local adaptation in hemiparasites should be observable in better hemiparasite performance when attached toA. capillarishosts originating FromEuphrasiapopulations. After one month of growth, the height and the number of leaves of hemiparasites were not affected by the origin of their hosts. The differences in growth were due to between population effects. The situation remained constant after three months. Hemiparasite biomass was not affected by the origin of the hosts. The percentage of hemiparasites surviving after one. two and three months was not affected by the origin of the hosts although there was a weak tendency towards better survival of hemiparasites with familiar hosts than with unfamiliar hosts. All variables used to measure hemiparasite performance during its complete life‐cycle gave only limited support for the local adaptation hypothesis. Nevertheless, the familiar hosts suffered less from parasitism as indicated by their higher biomass after the experiment. This suggests that there may be some interactions between hemiparasites and their hosts based on their spatial population structure and common history as competitors.