Search results for "Cuscuta europaea"
showing 5 items of 5 documents
RESISTANCE AND TOLERANCE IN A HOST PLANT–HOLOPARASITIC PLANT INTERACTION: GENETIC VARIATION AND COSTS
2002
Host organisms are believed to evolve defense mechanisms (i.e., resistance and/or tolerance) under selective pressures exerted by natural enemies. A prerequisite for the evolution of resistance and tolerance is the existence of genetic variation in these traits for natural selection to act. However, selection for resistance and/or tolerance may be constrained by negative genetic correlations with other traits that affect host fitness. We studied genetic variation in resistance and tolerance against parasitic infection and the potential fitness costs associated with these traits using a novel study system, namely the interaction between a flowering plant and a parasitic plant. In this system…
Relatedness affects competitive performance of a parasitic plant (Cuscuta europaea) in multiple infections.
2004
Theoretical models predict that parasite relatedness affects the outcome of competition between parasites, and the evolution of parasite virulence. We examined whether parasite relatedness affects competition between parasitic plants (Cuscuta europaea) that share common host plants (Urtica dioica). We infected hosts with two parasitic plants that were either half-siblings or nonrelated. Relative size asymmetry between the competing parasites was significantly higher in the nonrelated infections compared to infections with siblings. This higher asymmetry was caused by the fact that the performance of some parasite genotypes decreased and that of others increased when grown in multiple infect…
Local adaptation of a holoparasitic plant, Cuscuta europaea: variation among populations
2000
Locally adapted parasites have higher infectivity and/or fitness on sympatric than on allopatric hosts. We tested local adaptation of a holoparasitic plant, Cuscuta europaea, to its host plant, Urtica dioica. We infected hosts from five sites with holoparasites from the same five sites and measured local adaptation in terms of infectivity and parasite performance (biomass) in a reciprocal cross-infection experiment. The virulence of the parasite did not differ between sympatric and allopatric hosts. Overall, parasites had higher infectivity on sympatric hosts but infectivity and parasite performance varied among populations. Parasites from one of the populations showed local adaptation in t…
Interaction of a host plant and its holoparasite: effects of previous selection by the parasite
2001
If parasites decrease the fitness of their hosts one could expect selection for host traits (e.g. resistance and tolerance) that decrease the negative effects of parasitic infection. To study selection caused by parasitism, we used a novel study system: we grew host plants (Urtica dioica) that originated from previously parasitized and unparasitized natural populations (four of each) with or without a holoparasitic plant (Cuscuta europaea). Infectivity of the parasite (i.e. qualitative resistance of the host) did not differ between the two host types. Parasites grown with hosts from parasitized populations had lower performance than parasites grown with hosts from unparasitized populations,…
Population structure of a parasitic plant and its perennial host
2002
Characterization of host and parasite population genetic structure and estimation of gene flow among populations are essential for the understanding of parasite local adaptation and coevolutionary interactions between hosts and parasites. We examined two aspects of population structure in a parasitic plant, the greater dodder (Cuscuta europaea) and its host plant, the stinging nettle (Urtica dioica), using allozyme data from 12 host and eight parasite populations. First, we examined whether hosts exposed to parasitism in the past contain higher levels of genetic variation. Second, we examined whether host and parasite populations differ in terms of population structure and if their populati…