Current projects

  • Functional biodiversity and population health of bats and terrestrial small mammals in Panama
  • Effects of land-use changes on population health in important pathogen reservoirs and vectors in Africa
  • Olfactory choice of partners – immune system, smell receptors and their adaptive importance for the level of health in mammals
  • Selective mechanisms in host-pathogen coevolutionary processes
  • Functional importance of MHC variation in parasite and pathogen resistance

 

Local diversity of host populations as determinants of reservoir-borne virus dynamics

Very little is known about fundamental ecological mechanisms driving virus emergence from wildlife reservoirs. Current empirical and simulation approaches on the effects of anthropogenic modifications of ecosystems on wildlife health converge on the concept of the so-called dilution effect. According to this model, a decrease in host diversity appears to lead to an increase in the prevalence of pathogens and vice versa. Exact mechanisms driving the pathogen-related dilution effect remain unknown. Using an interdisciplinary, comprehensive approach we aim to identify ecological, behavioural and genetic (in particular, immunogenetic) factors potentially determining the dilution effect. We study bat and terrestrial small mammal populations (rodents and marsupials), as well as potential viral vectors, in three habitat types that differ in the degree of anthropogenic disturbance and contact probability to livestock and humans. The study is situated in a neotropical rainforest area (Barro Colorado Island, Panama) where we have access to an excellent research infrastructure (Smithsonian Tropical Research Institute, STRI). Furthermore, detailed knowledge of the composition of habitat and fauna and pilot data on the existence of several well-suited virus models that can be accessed by non-invasive sampling is available. Our central working hypothesis is that the dilution effect may fundamentally alter virus population dynamics, which in turn will influence the apparent evolutionary dynamics of viral populations. Increased evolutionary capacity of viruses may facilitate viral infection of closely related other species, ultimately leading to parapatric viral speciation and the crossing the host barriers. Studying the ecology of viruses in the context of their natural reservoirs helps to avoid mislead preventive measures against emerging viruses such as eradication programmes in wildlife.

PhD students: Stefan Brändel, Thomas Hiller, Julian Schmid.

In cooperation with Prof. Dr. Christian Drosten, Dr. Sandra Junglen (Virology, University of Bonn), Prof. Dr. Gerald Kerth (Zoology, University of Greifswald).

Funded by DFG Priority Program ‘Ecology and species barriers in emerging viral diseases’ (SPP 1596, Sommer SO 428/9-1, Tschapka TS 81/7-1).


Effects of land-use changes on the bacterial load of black-backed jackals (Canis mesomelas) and bat-eared foxes (Otocyon megalotis) in Namibia – a metagenomics approach to understand the ecological and molecular attributes affecting population health in important pathogen reservoirs and vectors

Anthropogenic land-use modification is supposed to stress wildlife with negative effects on health conditions. It also facilitates the contact between wildlife and human associated livestock potentially affecting the transmission rate of pathogens which might be one reason for the increasing number of novel infectious diseases threatening our biodiversity. In the farmlands of central Namibia, we  investigate how two prevalent modes of land-use (livestock versus game farming) and associated animal communities affect the health status of prominent canids and felids of southern Africa. We currently focus on black-backed jackals (Canis mesomelas), bat-eared foxes (Otocyon megalotis) and cheetahs (Acinonyx jubatus). All have been blamed as important pathogen reservoirs and vectors and occur in our study area also in modified habitats. We use a metagenomics approach applying next-generation sequencing technologies to qualify, quantify and compare the bacteria community (microbiome). Furthermore, we genotype the immune gene variability (MHC) of all species and investigate their impact on the pathogen load also using high-throughput methods and multivariate statistics. Our study will increase our understanding of the ecological and molecular attributes affecting population health of host and potential vector species as well as species barriers in viral and bacterial diseases. This will contribute to avoid eradication programs as a management tool during disease outbreaks.

PhD students: Sebastian Menke, Wasim Uddin, Master student: Matthias Meyer.

Funded by DFG (Sommer SO 428/10-1).

 

Olfactory choice of partners – immune system, smell receptors and their adaptive importance for the level of health in mammals

Olfaction plays a central role for mate choice in mammals, but there is a lack of understanding of the underlying proximate and ultimate aspects of olfactory signal evolution. Recent studies highlighted the importance of the major histocompatibility complex (MHC) for female choice which raises the question how volatiles, olfactory receptors and the MHC co-evolved in mammalian mating systems. The project applies a broad genomic approach using ‘next generation sequencing’ on two species with contrasting social and mating systems, the greater sac-winged bat in Costa Rica and the spotted hyena in Tanzania.

Postdoc: Dr. Pablo Santos.

In cooperation with Prof. Dr. H. Hofer, Dr. M. East, PD Dr. C. Voigt (IZW, Berlin), PD Dr. F. Meyer (Museum for Natural History, Berlin), PD Dr. M. Platzer (FLI, Jena).

Funded by Bund und Länder via Leibniz-Gemeinschaft, Pakt für Forschung und Innovation, Netzwerksantrag (PI: Prof. Dr. S. Sommer).


Host adaptations at the molecular and transcriptional level driven by a fast evolving pathogen, the rabbit haemorrhagic disease virus (RHDV) raging in European rabbits (Oryctolagus cuniculus)

Under natural conditions, pathogens are strong selective forces that drive coevolutionary processes. Studies on selective mechanisms in host species largely concentrated on analyses of major histocompatibility complex (MHC) sequence variation but did not take variance of expression in other genome-wide distributed relevant genes into account. This might be of evolutionary importance, in particular in response to fast evolving viruses. But how viruses remodel the host’s gene expression patterns and the genetic constitution of host populations is still elusive. We investigate the adaptive variance on the structural and transcriptional level caused by a severe contagious viral infection, using both experimental and field approaches. Our model, the rabbit haemorrhagic disease (RHD) raging in European rabbits (Oryctolagus cuniculus) provides ideal preconditions for this purpose due to already available long-term field as well as genomic data. We use gene expression profiling via microarrays, qRT-PCR, MHC-genotyping and the application of GBS (Genotyping by Sequencing) to discover candidate genes and expression patterns involved in host-pathogen interactions. This changes the focus from a few to thousands of genes and multiple regulatory mechanisms. It allows us to test current selection hypotheses in more detail to improve our understanding of causes and processes of evolutionary adaptations between hosts and pathogens.

Postdoc: Dr. Nina Schwensow (current position: University of Adelaide, Australia).

In cooperation with PD Dr. Jörns Fickel (IZW, Berlin) and Prof. Dr. Brian Cooke (University of Canberra, Australia).

Funded by DFG Priority Program ‘Host-Parasite Coevolution – Rapid reciprocal adaptation and its genetic basis’ (SPP 1399, DFG Sommer SO 428/7-1).

 

Functional importance of MHC variation in parasite and pathogen resistance

The genes of the major histocompatibility complex (MHC) are one side of a co-evolutionary arms race between host and their parasites. They are coding for cell surface glycoproteins in vertebrates and are responsible for the recognition of foreign antigens and thereby directly linked with parasite resistance and individual fitness. We study the functional important of MHC variation and expression on parasite burden in different Mammalian radiations (e.g. in rodents, rabbits, anteaters, cheetahs) in an ecological, evolutionary and conservation orientated context.

PhD student: Camila Clozato, Postdoc: Dr. Aines Castro