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Understanding the effects of anthropogenic impact on ecology, genetic diversity
and population health of wildlife
Changes in land use often lead to shifts in species composition and alter species abundance and their genetic diversity. While there is strong awareness of the direct negative consequences of habitat loss, fragmentation and degradation, invasive species, pollution, overexploitation and climate change, only recently have health issues been recognized as an emerging cause of species decline. Changes in parasite and pathogen pressure due to microclimatic effects and increased contact rates between wildlife, humans and their livestock potentially affect the prevalence and transmission rates of pathogens and might be one reason for the increasing number of novel infectious and zoonotic diseases threatening our biodiversity and personal well-being. Moreover, the loss of biodiversity alters many essential ecosystem services, such as pollination and habitat regeneration, on which humans and wildlife depend.
One fundamental question in conservation genetics and functional biodiversity research is to understand what drives and limits a species’ ability to adapt to current environmental and climatic changes affecting pathogen and parasite pressure. Pathogens and parasites form a natural part of our ecosystems and represent one of the major selective forces shaping host evolution, as they generally depend on ecological conditions of their host’s habitat. On the other side, the ability of a host population to resist pathogens depends, to a large extent, on its immunogenetic constitution. In vertebrates, genes of the major histocompatibility complex (MHC) play a key role in the host’s adaptive immune response and are of central importance in pathogen and parasite defense. When human impact upon a population causes a loss of MHC diversity, the ability to present pathogen antigens to the immune system is strongly impaired. Moreover, MHC variation in mammals is intrinsically related to an individual’s unique odor, which plays an important key role in social and reproductive behaviors. The MHC can directly shape olfactory cues (e.g. through the urinary presence of its gene products) or influence it indirectly: the MHC-dependent gut bacterial community, the so called gut microbiome, is assumed to control variation in individual odor profiles.
The gut bacterial community provides essential nutritional services to its host, is an important driver of mucosal immunity maintaining gut homeostasis, and provides protection against gut-invading pathogens. Thus, it can be a source of functionality but also potential pathogens, and therefore is, to varying degrees, under host genetic control. Shifts in its diversity beyond the normal range of variation leading to dysbiosis might cause an increasing susceptibility to enteric pathogens, which in turn may cause diseases. Especially, zoonotic enteric viral infections might pose a serious threat to gut bacterial homeostasis, increasing health risks by promoting co-infections.
In our research, we combine ecological field work with laboratory analyses (genetics, pathogen and parasite screening) in a wide range of different wildlife taxa, such as rodents, marsupials, lemurs, bats, lagomorphs, carnivores, birds and amphibians, in order to understand the effects of anthropogenic impact, changes in land use and associated shifts in animal communities on wildlife health and emerging zoonotic diseases. We have ongoing projects in Africa, Central and South America, Canada and Europe. We apply genomic approaches using high throughput sequencing technologies (Illumina®) to investigate the mechanisms by which neutral (microsatellite, SNPs) and adaptive genetic diversity (MHC, TLR) act on evolutionary processes. We study the gut and skin microbiome of different wildlife hosts in order to understand the effects of ecological, genetic and environmental factors but also the implication of viral and fungal infections on the ‘normal’ range of bacterial variation. We investigate the health status of wildlife individuals by monitoring ecto-and endoparasites, bacterial and viral pathogen loads by microscopic quantification and by means of microbiome sequencing, metagenomics, metabarcoding and viral genome assays. The combined data sets are analyzed by state-of-the art bioinformatics and statistical tools.