Research and CV (International Version)

Research

All biological communites show temporal variations in species composition and in the size of the various populations, as well as variations in biological interactions as results of successional processes, of climatic shifts or of invasive species. Many of these and other ecological changes have been strongly enforced by human activities or are even totally unprecedented for nature. Changes and fluctuations may be observable within years to decades. Yet, there also occur various evolutionary changes, often at a slower pace, manifesting biological changes only after decades to centuries or on an even much longer perspective. Among these are changes in genotype frequencies and other genetic rearrangements which again may result from natural or anthropogenic changes of the environment. These alterations may affect physical appearance, physiological properties or the composition of personality traits. Ecological and evolutionary shifts go hand in hand and shape animal, plant and human populations, their health and their interactions. 

Our research, our teaching and our student excursions have led us to different parts of the planet. A multi-national excursion with students from different countries of the Middle East and a selected group of Frankfurt students is seen on the photo on the top left. A central issue of our research and teaching is the phenomenon of global change and biodiversity loss resulting from the strongly increasing dominance by the more than 7.5 billion humans on earth. This number is roughly 100 times higher than any similarly sized free-living vertebrate species may ever  have shown in the history of the planet.

With his team, Bruno Streit did research at the universities of Konstanz (Germany), Basel (Switzerland), Stanford (California) and, since 1985, Frankfurt. Studies were mostly performed using and analyzing selected freshwater and land populations. A complex ecosystem studied over a long period was and still is the Rhine River system: This  European river has been colonized massively by invasive invertebrate and vertebrate species from other aquatic systems of Europe and from overseas during the last decades. So, after the large-scale hydrological modifications of this river system in the 19th and 20th century, its biological community has been transformed into a largely new biocenosis within the past decades. Only a few of the original invertebrate species are still found in an appreciable number, such as the freshwater limpets (photo in the second row  center). These aquatic pulmonate snails have been studied by Steit and his team in large detail from a physiological, ecological, ecotoxicological and evolutionary aspect since the 1970ies and help us to understand the ecological role and the evolutionary peculiarities of hermaphroditic constituents (i.e. animals, where the individuals have both, male and female sexes) of biota. We are currently studying phylogenetic and phylogeographic relationships of all of the European species of this genus (S. Klaus, B. Streit, and others).

Most of our research is based on empirical data, experiments, and modelling of  selected animal species. We use methods from field and aquatic biology and combine results from morphological, physiological, behavioural, and molecular genetic studies and are using a variety of statistical analyses. A central research focus is currently set by Dr. Sebastian Klaus,  senior scientist and assistant professor ('Privatdozent'), supported by his own DFG grant (a grant from the German Science Foundation). He is studying in detail, together with his students, phylogenetic relationships between freshwater crabs (photo bottom right) in East Asia and in other areas of the world. In combination of the above-mentioned methods with fossil data he could disentangle various aspects of their evolution and help to understand past river catchment fluctuations, as resulting from variable sea levels and erosional landscape modifications. He detected biogeographical separations and fusions of formerly separate biogeographical areas and could thus contribute to the reconstruction of ancient biogeographical entities and separations as consequences of plate tectonics and pleistocene sea level fluctuations. His geographic focus originally was in the Mediterranean basin, today it is in East and Southeast Asia.

Another important research line in the past years and still going on was the study of ecology, ethology and evolution of tropical freshwater fish species from the Poeciliidae family (guppy, molly; some of their species are appreciated as small ornamental fish held in home aquaria). This biological system was introduced in our lab by Dr. Martin Plath, now professor at the University of Xian/Yangling in China, who still functions as a collaboration partner and supervisor. We try to understand social communications and interactions in the genus Poecilia, especially concerning courtship behaviour and related aspects of their reproduction and communication biology (PhD theses by D. Bierbach, J. Jourdan, C. Sommer-Trembo, and others). Also aspects of geographic distribution, invasion of European aquatic systems und speciation in this fish family were studied.

Water fleas of the genus Daphnia are excellent candidates to study various ecologcial and evolutionary processes, as these tiny planctonic animals (1-3 mm in length, see photo at the bottom) are easy to rear and their genome has been fully sequenced. Our main research focus was on the species complex typically inhabiting  large lakes, i.e. Daphnia galeata, D. cucullata, D. hyalina. The studies, mostly designed and supervised by Dr. Klaus Schwenk, now professor at the University of Landau, has recently come to an end. Among other findings, we could detect relationships between the dominance of the one or the other species depending on longterm climatological as well as short-term civilizational influences of the species composition in the respective European lakes. 

Also various studies on mammal species are currently facing finalization. One of them is a regional project where we analyzed European rabbits (Oryctolagus cuniculus, see large photo), originally introduced from the Iberian Peninsula into Central Europe probably since the Middle Ages. We studied aspects of their population biology, parasitology and ethology, comparing urban with rural populations (PhD thesis by M. Ziege, and others). We could show that the approximately 4.000 to 6.000 city dwellers in Frankfurt reveal simpler social entities, but at the same time they experience less environmental stress than their rural relatives, which are meanwhile in decline nearly everywhere in Central Europe.

Other mammal species studied are south-east Asian tarsiers (in cooperation with Dr. Stefan Merker, State Museum for Natural Sciences, Stuttgart). These are tiny tree-dwelling primates that live nocturnally and are exclusively carnivorous. These dwarfed representatives of the very taxonomic group, where humans belong to also, separated some 50 to 60 million years ago from the other "higher" primate lines and thus from the line that eventually also led to Homo.

Thanks to a cooperation with WWF Germany, a PhD candidate (S. Ziegler) was able to successfully work on ivory profiling by isotopes (C-13, N-15, O-18, δ2H, S-34), by that helping  authorities to find out approximately the area of origin, where the legal or non-legal ivory comes from. In an additional study (S. Merker, S. Ziegler, B. Streit) we are currently analyzing phylogenetic and phylogeographic relationships of African elefants, based on populationsgenetic data.

In cooperation with different partners (M. Plath, T. Wronski, M. Pfenninger) we studied aspects of behaviour and analysed phylogenetic relationships of Arabian gazelles (Gazella dorcas and other species). Population size shifts in prehistorical and historical times were estimated by applying coalescent theory on nucleotide sequences of the cytochrome b gene and a 540 bp fragment of the mitochondrial control region. The species have been mentioned various times also in the Bible, but now have disappeared from most of their original ranges.

August 2017


CV Bruno Streit

Studying natural sciences with a focus on zoology at the University of Basel (Switzerland), Bruno Streit graduated with studies on limnology. His doctoral thesis was on ecophysiological aspects and the energy and carbon flow of the European freshwater limpet Ancylus fluvaitlis. The studies were performed at the Limnological Institute at Konstanz (Germany). He continued as a postdoc at the same lab with studies on the bioaccumulation and ecotoxicity of pesticides in aquatic environments. After his return to the University of Basel he completed his 'habilitation' (a qualification degree to become a formal professor) in zoology and continued by taking over official chair duties (Lehrstuhlvertretung), focussing in research on soil ecology and heavy metal ecotoxicology. In 1982 he moved to Paul Ehrlich's lab at Stanford University (California), from where he returned 26 months later to Europe to  take over a full professorhip at Frankfurt on April 1, 1985. In the following, research topics of his group concentrated on environmental science and ecotoxicology, and on ecology and evolutionary biology. He held various positions within the University, such as dean for several years, founding director of the Institute of Ecology and Evolution and cooperation member and P.I. of the Biodiversity and Climate Research Centre, a joint institution of Goethe University and Senckenberg from 2008-2014 (today part of Senckenberg). One of his more political goals was the strengthening and tightening of  interactions between Goethe University and non-university institutions of the Frankfurt area, as far as they work on issues of biodiversity, nature conservancy and sustainabilty management. Thus he was one of the founders and became spokesman since the beginning (2004) of BioFrankfurt, Network for Biodiversity (www.biofrankfurt.de). Currently he is working and teaching as a Senior Professor for ecology, evolutionary biology and organismic diversity. He is  author of more than 230 scientific papers, author/coauthor or editor of 12 books in German, English and Vietnamese as well als of various special topic issues of scientific journals and brochures. Furthermore, he is active in academic evaluations, public talks, presentations and in guided tours through the Riedberg Science City.