Zusammenfassung
Recent studies suggest that parasites (interpreted
broadly to include viruses, bacteria, protozoans and
helminths) may influence the numerical magnitude or
geographical distribution of their host populations;
most of such studies focus on the population biology
and epidemiology of the host-parasite association,
taking no explicit account of the genetics. Other
researchers have explored the possibility that the
coevolution of hosts and parasites may be
responsible for much of the genetic diversity found
in natural populations, and may even be the main
reason for sexual reproduction; such genetic studies
rarely take accurate account of the density-and
frequency-dependent effects associated with the
transmission and maintenance of parasitic
infections. This paper aims to combine epidemiology
and genetics, reviewing the way in which earlier
studies fit into a wider scheme and offering some
new ideas about host-parasite coevolution. One
central conclusion is that `successful' parasites
need not necessarily evolve to be harmless: both
theory and some empirical evidence (particularly
from the myxoma-rabbit system) indicate that many
coevolutionary paths are possible, depending on the
relation between virulence and transmissibility of
the parasite or pathogen.
Nutzer