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How does host immunity shape on parasite life history strategies?
Mortality patterns impose selection on when and how much organisms reproduce. For instance, mammals with low life expectancy live fast and die young; those with long life expectancies typically reproduce later in life and produce fewer high quality offspring.
Host immunity is one of the major sources of mortality on parasites and pathogens; enhanced pathogen killing via host immunity is the aim of many vaccination programmes. Will life history evolution prompted by vaccination lead to pathogens that are clinically beneficial or clinically detrimental? Many of the same arguements also apply to chemotherapy.
Natural levels of immunity are highly variable, and are often affected by the force of infection, which is itself a function of pathogen reproductive rates. Thus, the population dynamical consequences of life history evolution shapes that evolution.
We are interested in the proximal and evolutionary consequences of immunity for parasite life history in malaria (see many of the other research questions, but we are also asking life history questions of gastrointestinal worms. Here, size is fecundity (and often virulence), but getting big takes time. Do GI nematodes mature earlier in more immune hosts, thus giving up the fecundity advantages of longer prematurational growth, but ensuring that they do not die before they reproduce? Are there density-dependent immune factors which shape worm size and reproduction? Are they using host immune factors as developmental triggers to optimise their life histories?
Group members involved:
Collaborators: Mark Viney