LTREB: A long-term Study of Host-parasite Interactions

Indiana University, Bloomington IN

Investigators

Abstract

Lively 0128510 Explaining the widespread distribution and maintenance of genetic recombination is widely regarded as one of the most interesting challenges facing evolutionary biologists, and a large number of ecological and genetical hypotheses have been suggested to explain why clonal reproduction has not generally replaced genetically recombining individuals in populations. Contrasting these alternatives has proven difficult, but the effort is greatly aided by studies of populations in which clonal and recombinant individuals coexist. Such mixed populations are common in the freshwater New Zealand snail, Potamopyrgus antipodarum, which has been used as a model system for evaluating different hypotheses. In past studies, no support for the lottery hypothesis, the reproductive assurance hypothesis, or the tangled bank hypothesis has been found. In contrast, past work has shown that the frequency of recombinant individuals is spatially coupled with the prevalence of infection by larval trematodes. This result is consistent with the idea that time-lagged, frequency-dependent selection by parasites prevents the elimination of recombinant hosts by clonal hosts - the Red Queen hypothesis. But, direct tests of this hypothesis are still needed. This LTREB research will allow measurement in mixed populations of the frequency of recombinant and clonal individuals over time. Long-term data will provide a test of the hypothesis that time-lagged selection by parasites prevents the replacement of recombinant individuals by clonal individuals in natural populations.