BIOB50H3 Chapter L#14: Lecture #14 reading
Parasites can influence host population cycles
- Peter Hudson manipulated the abundance of parasites in red grouse populations on
moors in Northern England
They studied change in red grouse numbers in 6 replicate pop. Over the course of 2
population cycles in 2 of the 6 study pop., they treated as many grouse as they
could catch in 1989 and 1993 with drug that kills parasitic nematode, in 2 other
study pop. Grouse were caught and treated for parasites in 1989 only, the remaining
2 groups were controls in control pop., red grouse numbers crashed as predicted
in 1989 and 1993
(b/c pop. Cycle)
although parasite
removal did not
completely stop
the population
cycle, it did reduce
the fluctuation in
grouse numbers
thus: see that
parasites influence
and might be the
primary cuase of
red grouse population cycles
- These pathogens also play important role in human pop. Cycles
Simple models of host-pathogen dynamics suggests ways to control the establishment and
spread of diseases
- These models differ from other models b/c
1. The host population is subdivided into categories such as susceptible indiv.,
infected indiv., recovered and immune indiv.
2. Often necessary to keep track of both host and pathogen genotypes b/c
genotypes may differ greatly in their resistance to the pathogen and pathogen
genotypes may differ in their ability to cause disease
3. Depending on the pathogen, it may be necessary to account for other factors that
influence its spread, such as (1) differences in the likelihood that hosts of diff.a ges
will become infected; (2) a latent period in which the host indiv. Is infected but
cannot spread the diseases; and (3) vertical transmission, spread of the disease from
mother to child (i.e AIDS)
- here, we’ll only consider a simple model that looks at: whetehr a disease wll spread only
if the density of susceptible hosts exceed a critical threshold density
Document Summary
Peter hudson manipulated the abundance of parasites in red grouse populations on moors in northern england. They studied change in red grouse numbers in 6 replicate pop. Over the course of 2 population cycles in 2 of the 6 study pop. , they treated as many grouse as they could catch in 1989 and 1993 with drug that kills parasitic nematode, in 2 other study pop. Grouse were caught and treated for parasites in 1989 only, the remaining. 2 groups were controls in control pop. , red grouse numbers crashed as predicted in 1989 and 1993 (b/c pop. Cycle) although parasite removal did not completely stop the population cycle, it did reduce the fluctuation in grouse numbers. Thus: see that parasites influence and might be the primary cuase of red grouse population cycles. These pathogens also play important role in human pop. Simple models of host-pathogen dynamics suggests ways to control the establishment and spread of diseases.
