Disease Ecology and Evolutionary Genetics

Disease Ecology and Evolutionary Genetics

We are studying the interaction between animal and pathogen and the consequences that an infection has on the survival and reproduction of the animal. Why do some animals become ill and others do not? How are their migrations affected? What role do collective interactions within a flock play in a response to disease? Why and how does, for example, a mallard die? And what constitutes the immuno-genetic basis of all this?

Living in an aquatic habitat, mallards are exposed to a diverse and rich fauna of microorganisms (bacteria, viruses, fungi, and parasites). Most of these microorganisms are harmless for the birds. There are, however, several pathogens, such as the influenza virus, to which the birds are also exposed. During evolution, most pathogens have reached a certain balance with their hosts, the birds: the host does not become ill despite optimal propagation of the virus. If the pathogen mutates, for example in the case of the highly pathogenic influenza (avian bird flu), or if the host's immune system is not able to control the infection, there is no longer any equilibrium and the host experiences disadvantages. Migratory lifestyle challenges the immune system even more because migration is an intense form of exercise and therefore impacts the energy budget of the whole organism – incl. energetic costs of immune defense. Additionally, encountering diverse locations during migration brings the organism into contact with a sundry of more pathogens. Dense aggregations of individuals on stopover sites and inter-individual interactions and the collective behaviour of whole groups are characteristic for shaping emergence of infectious diseases in a small-world network.

It is the immune system of a host that determines how the defense against pathogens is carried out. Vertebrates have evolved a complex immune system that comprises, besides physical barriers (e.g., skin), an innate component with which these animals were born and that does not change throughout their lives, and an adaptive component which continuously accommodates for changes in the pathogen community. The genetic basis of the immune system carries the signature of millions of years of evolution. Comparative analyses of immune genes between individuals within a species as well as comparisons between closely and distantly related duck species are key in understanding immune pathways.

Among (migratory) waterfowl, the mallard is most familiar to researchers and a preferred model for immuno-ecological studies. The mallards at the Max Planck Institute for Ornithology in Radolfzell are held in our new aviaries for short experiments or for breeding. They are tested for pathogens and different parameters of their immune systems are studied. Then, they are fitted with a GPS and acceleration logger, in addition to heart-rate and body-temperature loggers before they are released and observed by this telemetry while roaming in their natural surroundings. Other species of ducks can also be housed and bred for comparative studies of the genetic basis of their immune system, or for deciphering their evolution into distinct species with immunological traits of which some can be distinct, and others shared.

The immune system of birds is adapted very well to several pathogens (e.g. Salmonella, avian influenza) that can be transmitted to humans and are potentially lethal. [more]
True geese are members of the order waterfowl (Anseriformes) which contain many species with high relevance as natural hosts of avian influenza virus (AIV). [more]
My project aims at improving our knowledge of how the immune system works in a natural context, using the mallard (Anas platyrhynchos) as a study system. I will use molecular tools to study genetic variation and evolution of the innate immune system [more]
Deliberate release of species in nature is a common procedure to increase threatened populations, or to increase harvested populations. The practice of augmenting an already viable population for harvest reasons is frequently [more]
Differentiation between males and females is a basal asset of sexually reproducing organisms. Yet, sex determination systems that initiate this differential development are highly diverse across the animal kingdom. [more]
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