GENETICS OF HOST-PARASITE INTERACTIONS

The evolution of host susceptibility or resistance to parasites has im portant consequences for the evolution of parasite virulence, host sex ual selection, population dynamics of both host and parasite populatio ns, and programs of biological control. The general observation of a f raction of individuals within a population that is not parasitized, an d/or the variability in parasite intensity among hosts, may reflect se veral phenomena acting at different levels of ecological organization. Yet, host-parasite coevolution requires host susceptibility and paras ite virulence to be genetically variable. In spite of evolutionary and epidemiological implications of genetic heterogeneities in host-paras ite systems, evidence concerning natural populations is still scarce, Here, we wish to emphasize why we need a better knowledge of the genet ics of host-parasite interaction in natural populations and to review the evidence concerning the heritability of host susceptibility or res istance to parasites in natural populations of animals.