Prof. Dr. Horst Thieme (School of Mathematical and Statistical Sciences, Arizona State University): Can infectious pathogens drive their host populations into extinction? And what role may predators of the host play?
am Mittwoch, 05.07.2017 15:15 im Raum M4
Amphibian decline and disappearance
have renewed interest in the part
infectious diseases (without Allee effects or reservoirs) have
in the extinction of their host species.
In simple SI epidemic and endemic models, three classes of
incidence functions are identified for their
potential to be associated with host extinction:
Upper density-dependent incidences are never associated with host
Power incidences that depend on the numbers of infectives and susceptibles
by powers strictly between 0 and 1 are associated with
initial-constellation-dependent host extinction
for all parameter values.
of which frequency-dependent incidence
is a very particular case, and power incidences are associated with global
host extinction for certain parameter constellations
and with host survival for others. This leaves the question undecided that
motivated this analysis, namely
whether ranavirus epidemics can drive tiger
salamander populations into extinction. Laboratory
infection experiments with salamander larvae are equally well fitted by
power incidences and certain upper density-dependent incidences such as the
binomial incidence and do not rule out homogeneous incidences
such as an asymmetric frequency-dependent incidence either.