Veijo Kaitala - Ecology and Evolutionary Biology

Photo: Tiina Airamo

Opportunistic pathogens: virulence, disease dynamics and evolution

Professor Veijo Kaitala

The current theme is internationally a new opening among the themes studied in the field of epidemiology. The central idea of the study is the observation that many pathogens are able to survive and grow in the outside-host environment, e.g., via saprotrophism. These kinds of pathogens are commonly referred to as opportunists as the host specificity is often low and growth within the specific host is an alternative but often very efficient reproductive strategy. Thus, disease dynamics are likely to differ between opportunist and obligatory pathogens, which are completely dependent on their hosts for reproduction and survival. Opportunist pathogens are also plausible ancestors of obligatory pathogens. The opportunist lifestyle is a pathway through which all obligatory pathogens must evolve, and the understanding on the evolutionary processes that lead to obligatory life history, or selection pressures that prevent it, are of fundamental importance.

We develop the epidemiological theory starting from a largely unfamiliar viewpoint where pathogen eco-evolutionary dynamics is modeled assuming that the pathogen is embedded within a realistic food web where the organism has to face e.g. the predators and parasites, and resource competition.

In particular, two aspects is addressed in the project. The first one is biological control. Pathogens can be controlled in the environment by phages or by predators. The defense and its consequences on the life history traits or energy allocation of pathogens differ depending on the type of the enemy against which they develop defense. Another aspect of the project is the evolutionary one. Here the first question is the initial evolution of the pathogenic strain from a non-pathogenic one, and the spread of the pathogens in the environment. The second question is the evolutionary defense of the pathogens against biological control. The effectives and ecological dynamics and evolutionary both initial evolution and the consequences of treatment of using either phages or predators in biological control will be studied.