Summary of my research interests
All my research contributes to the better understanding of biological processes in diverse environments, including biological responses to climate change, pollution and fragmentation. I also aim to include findings in these fields in conservation policy making, to allow science a direct input and effect on conservation in Europe. Check my summaries of projects I have worked in during my career.
General scientific interest
Due to the simple fact that the amount of heritable genetic variation is the ultimate determinant of populations’ potential to respond and adapt to environmental changes, quantitative and molecular genetic methods have assumed an increasingly central role in our attempts to reconstruct, understand and predict the likelihood, pace and direction of evolutionary changes in the wild. My research is directed to strongly contribute to the understanding of processes creating and maintaining diversity, focusing on genotype x environment interactions in sexually as well as asexually reproducing species. I use both, genetical as well as ecological methodology, to achieve results of interest for a wide audience in ecological research.
Future research goals
My research goals comprise a wide range of different subjects in evolutionary ecology and genetics. There are many interesting systems of sexual and asexual species, offering a huge range of possibilities for future research. Generally, I am open-minded, and even eager to also start something new, if the question is challenging and contributes to the understanding of processes in wild populations. Here, I will just state those ideas, which have developed over my last years of research, which I have mostly spent with frogs.
My study on the colonization history of R. temporaria in Fennoscandia has revealed a contact zone of two genetically divers lineages in northern Germany. However, we failed to exactly describe the range and distribution of this contact zone. The knowledge of such a contact zone is of wide interest as in detail molecular ecological studies can assess the degree of newly formed genotypes and their performance in different environments. Especially in light of cryptic glacial refugia, results of such a study may substantially contribute to the understanding of local adaptation and colonization ability of a widely distributed species. Further, I am strongly interested in the extension of my research on reproductive success in R. temporaria under different environmental conditions. Here, a comparison of reproductive strategies in low altitude and high altitude populations will extent my current data set, and will lead to a deeper understanding of the common frogs ability to colonize a huge diversity of habitats. The latter idea, however, can also be transferred to any other species, with a similar colonization ability.
Further, studies have shown that hybridogenesis has an impact on both the genetics and ecology of species. It is of high relevance to understand, if interspecies gene flow mediated by hybridogenesis increases the adaptability of species. The successful establishment of many R. ridibunda populations far from the center of distribution in Central Russia supports such a hypothesis. A mixture of different lineages and an interspecies gene flow due to hybridogenesis might considerably contribute to a shift in the ecological niche of this species. Assessing the ecological niche of R. ridibunda in different regions of its distribution range, and comparing the niche width to the genetic background likely contributes to our understanding of local adaptation and the influence of hybridogenesis on the niche width of species.
Reproductive success in the wild
Studies of marginal populations, and their role in speciation and diversification processes, have had a central role in the development of the modern evolutionary synthesis. Despite of this relationship between emergence of modern evolutionary biology and study of marginal populations, we are still largely ignorant of possible major intra-specific evolutionary diversifications within species occupying large geographical ranges. One reason for this is that autecological studies of marginal populations are often logistically difficult, not least because they often inhabit areas not easily accessible for researchers.
My studies on the reproductive success in a wild population of the common frog R. temporaria contribute significantly to the understanding of selection pressures under harsh environmental conditions. The common frog is an ideal model organism, as the challenge for poikilothermic animals posed by cold climate and short summers is reflected in the fact that only one out of the 209 species of European amphibians has managed to establish viable populations in the subarctic zone.
Human introduction of R. ridibunda and its genetic impact on the species
The impact of introduced species on native species, indigenous communities, and ecosystems is manifold, threatening biodiversity on both the genetic and the species level. Concerns about introduced species are increasing in many fields, such as biology, agriculture, transportation, and economics, due to the scales of human mobility. Therefore, invasive species have been a research target in a large body of studies, but the complexity of the invasion process hardly allows predicting with any degree of accuracy which introduced species reacts in what way.
To help improving rather inaccurate predictions of the development of introduced species I ecologically and genetically investigated the waterfrog species Rana ridibunda, of which different genetic lineages were introduced to various European countries, especially to France for reasons of consumption. The range of R. ridibunda dramatically expanded in France rather recently. Further, the species now occupies habitats formerly inhabited by indigenous waterfrog taxa in Switzerland, France, and Britain. Besides the urge for research given by the increasing range expansion, a unique combination of factors makes the western Palearctic waterfrog complex an interesting system to investigate a species’ possible invasiveness. The waterfrog complex encompasses different hybridogenetic systems, each comprising the species R. ridibunda, a second parental species (R. perezi, R. lessonae), and a hybridogen (R. kl. grafi, R. kl. esculenta). These hybridogens are fertile, as a result of the exclusion of a whole genome and the subsequent endoreduplication of the remaining one. Usually, these hybridogens reproductively mimic R. ridibunda, and for the maintenance of their lineage backcross with the second parental species. In such a hybridogenetic system the R. ridibunda genome therefore is involved in sexual and asexual reproduction, fulfilling an important criterion of invasiveness. Additionally, the hybrid increases the relative amount of R. ridibunda gametes in a population, and was assumed to strongly support the reproductive success of R. ridibunda and its colonization ability. Further, most of the R. ridibunda lineages in France have been introduced from several different countries of origin so that the current populations represent a genetically highly variable mixture of different genetic lineages. The ecological limitations might be a constrain reducing the invasibility of R. ridibunda, but might be overcome by the genetic diversity of R. ridibunda in the study region, enabling adaptation to different environments. I compare the genetic diversity of R. ridibunda in France comparing several regions with different introduction histories and species compositions.
Scientific competence
I know a lot of different methods in the lab as well as in the field.
Field techniques
Collecting (insects, amphibians, reptiles)
Manipulation of amphibians (frogs)
Capture - Recapture (Individual marking)
Morphometrics
Lab techniques
DNA extraction (salt, phenol, and rapid)
PCR (Polymorphism Chain Reaction)
Sequencierung
Microsats
Flowcytometry
Skeletochronology
Artificial insemination
Common garden