Ichthyology

Responsible curator: Dr. Lukas Rüber

My main research interest is in line with one of the central themes in evolutionary biology, namely understanding the processes that contribute to the origin and maintenance of biodiversity. The diversity of recent species is not equally distributed among taxonomic groups and across the globe - a small number of clades accounts for a large part of the world's diversity and a number of relatively small areas with high levels of endemism are populated by unusually large numbers of species. I study patterns and processes of diversification at different spatial and temporal scalesby focusing on fish adaptive radiations and biodiversity hotspots. My main research themes are:

1) Biodiversity of Southeast Asian freshwater fishes.Some of the world's hyperdiverse areas, but at the same time most threatened biota are located in Southeast Asia. These biodiversity hotspots comprise important systems for investigating the processes of evolutionary diversification; a prerequisite to document, explain, and conserve the diversity of life we observe today. The freshwater ichthyofauna of Southeast Asia with around 2100 valid species, and an estimated total number of 3000 species is still poorly known, as well as the biogeographic history of the region. One of my long-term goals in this research area is to produce comparative DNA data for a number of Southeast Asian freshwater fish clades (e.g. labyrinth fishes, snakeheads, cyprinids) to address general questions regarding the origin and maintenance of biodiversity (biogeography, diversification patterns, community assembly). A focus is made on ichthyofauna of the Southeast Asian peat swamp forests, a diverse, but very neglected fauna that is critically endangered due to large scale habitat destructions.

2. Evolution of the gobies.Gobies are small fishes normally between 4 to 10 cm inhabiting most freshwaters, brackish, and marine habitats. With over 2500 species, gobies show a spectacular variety in morphology, behaviour, and ecology. They are well renown for their associations with various marine invertebrates, their cleaning behaviour, or their mutualistic associations with snapping shrimps. Major ecological shifts associated with evolutionary novelties in morphology or physiology characterizes many gobioid groups, as for example the amphibious mudskippers and the amphidromous freshwater rock-climbing gobies. By virtue of their abundance and diversity in coastal ichthyoplankton, cryptic tropical reef fish communities, freshwater streams of tropical oceanic islands, and estuarine benthos, gobioids play key roles in community structure and trophic dynamics of almost all coastal, shallow, marine habitats. Despite their evolutionary and ecological importance, phylogenetic intrarelationships of gobioids are poorly understood. Base on molecular phylogenetic I study various aspects of the evolutionary history of this fascinating group.

3. Mechanisms of speciation in cichlids.Since the publication of Darwin’s 'On the origin of species' 150 years ago, speciation remains one of the most exciting and at the same time least understood evolutionary processes. Recent advances in speciation theory have been both inspired and informed by the adaptive radiations of cichlids of the East African Great Lakes. These lakes harbour over a thousand species, and represent over 10% of the worldwide freshwater fish diversity. In the focus of my research are the cichlid species flocks of Lakes Tanganyika and Natron-Magadi.