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

We experimentally studied the role of local adaptation and the co-evolution ary relationship between an annual. endangered root hemiparasite Euphrasia rostkoviana and its main host Agrostis capillaris. According to our hypothe sis, the existence of local adaptation in hemiparasites should be observabl e in better hemiparasite performance when attached to A. capillaris hosts o riginating from Euphrasia populations. After one month of growth, the heigh t 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 e ffects. The situation remained constant after three months. Hemiparasite bi omass was not affected by the origin of the hosts. The percentage of hemipa rasites surviving after one, two and three months was not affected by the o rigin of the hosts although there was a weak tendency rewards better surviv al of hemiparasites with familiar hosts than with unfamiliar hosts. All var iables used to measure hemiparasite performance during its complete life-cy cle gave only limited support for the local adaptation hypothesis. Neverthe less, the familiar hosts suffered less From parasitism as indicated by thei r 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.