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Ecologists and evolutionary biologists have become increasingly aware that diseases can be a major factor in determining the population dynamics and evolution of their hosts, but we still know little about how they affect the dynamics and structure of communities. Diseases can connect the population dynamics of different species that would otherwise not be related to each other, or alter the dynamics of their competitive or predator-prey interactions. The dynamics of host-disease systems are also strongly influenced by population structure and the interaction among cohorts, including cannibalism. In my research I use different modeling approaches to examine and predict the effect of diseases on population dynamics and community structure and the evolution of life-history strategies.
Diseases, Community dynamics & the role of Biodiversity Most diseases are able to infect multiple species within a community. As a consequence, cross-species transmission is common, including transmission between us and other animals. Cross-species transmission is often associated with disease emergence and has thus commonly been seen as a negative factor. However, the effect of transmission between species will depend on the specific ecological conditions and life histories of the host and the diseases. In a recent collaborative work with Janis Antonovics we show that sharing a pathogen can be beneficial for species depending on the transmission function, and sharing might actually rescue a host from its otherwise inevitable extinction. This results from what we term a "frequency-dependent dilution effect", in which the decrease in disease incidence is a result of the direct increase in biodiversity. In this case the disease can generate apparent mutualism between species, and sharing the pathogen among multiple species may actually limit the spread of disease. This suggests that diverse systems are more resistant to diseases, but it also suggests that changes in the abundances of hosts and host community structure in general can lead to epidemic spreads of disease in other members of the community (Rudolf & Antonovics, 2005). Cannibalism, diseases and parasitoids
Similarly host-parasitoid systems with a cannibalistic host differ from standard parasitoid systems in that the host can actually prey on its parasitoid. This partial reversal of the predator-prey relationship has important implications for the population dynamics of host-parasitoid systems and the evolution of life histories of parasitoids as well as their hosts. In my research I use a modeling approach including ESS analysis to examine the evolutionary dynamics of such systems.
Relevant publications: Rudolf, V. H. W., and J. Antonovics. 2005. Species coexistence and pathogens with frequency-dependent transmission. American Naturalist 166:112-118. |
Cannibalism can have important impacts on the dynamics of diseases and of
parasitoid-host systems. In many organisms cannibalism is a common mode of
transmitting a variety of parasitoids and diseases, including the degenerative prion disease Kuru in the Fore people of New Guinea. Cannibalistic systems
differ from standard host-disease systems because cannibalism actively
removes infected individuals within the population, which means that the
host is imposing mortality on the disease. However, the evolutionary and
population dynamics of such systems are poorly understood. Using mathematical models
I analyze the dynamics of such system,
i.e. the
conditions under which disease can invade and spread successfully
in cannibalistic populations and when the disease or the host are driven to
extinction. Our recent model results show that diseases can only spread
within a population with group cannibalism i.e. if multiple cannibals share a prey
individual. Such social group
cannibalism was commonly found in past cannibalistic human tribes. On a
meta-population scale, a combination of intraspecific necrophagy within villages and group
cannibalism resulting from attacks on neighboring villages would be
sufficient to allow the spread of prion diseases across landscapes.
(Rudolf & Antonovics,2007,
