Master projects at the Zoological Institute

Below is a short outline of some of the areas in which groups in Zoology offer master projects. Further topics can be discussed with the group leaders. The projects are deliberately vague, as the details shall be worked out with the candidates. The development of the details of a project is an important part of doing a master thesis.

Interested candidates should contact the group leaders directly.

Group: Walter Salzburger

Ecological speciation in East African cichlid fishes

The adaptive radiations of cichlid fishes in the East African Great Lakes represent the most species-rich and diverse animal adaptive radiations. More than 1500 cichlid species have evolved in lakes Tanganyika, Malawi and Victoria in a period of no more than a few million years only. The evolutionary success of the cichlids can be attributed to several ecologically relevant and, hence, naturally selected traits such as mouth morphology, but also to sexually selected traits such as coloration (see Salzburger 2009; Molecular Ecology). This project aims to test whether ecological speciation is the causal factor of diversification in cichlids from Lake Tanganyika. To this end, closely related species pairs will be compared in terms of their ecological adaptations.

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The adaptive radiation of the Tropheini from Lake Tanganyika

Lake Tanganyika is the oldest of the three East African Great Lakes and harbors the morphologically, ecologically and genetically most diverse assemblage of cichlid fishes. Unlike in lakes Victoria and Malawi, where only one group of cichlids (the haplochromines) have radiated, the Tanganyikan cichlid assemblage consists of several parallel adaptive radiations. One of these are the Tropheini, a group of about 30 mostly rock-dwelling species. The aim of this project is to study the adaptive radiation of the Tropheini by integrating phylogenetic and population genetic analyses with eco-morphological assessments of all species belonging to this group.

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Group: Dieter Ebert

The ecology and evolution of host-parasite interactions in natural populations

Parasites and pathogens are the largest functional group of species on earth. In natural ecosystems, the vast majority of organisms suffer from some forms of infection. This goes hand in hand with reduced fecundity and survival, lower chances of mating and even with the extinction of local populations. Surprisingly, we still know only very little about the impact of infectious diseases on the ecology and evolution of their hosts. In a long term field project in Southern Finland, we study the impact of infectious diseases on host species of the genus Daphnia. Populations of Daphnia occur in small rock pools on the Skerry islands in the Baltic Sea. In our project we combine experimental work in the field with observations from natural populations. Within our Finland-project several options for master projects are open. The details of project will be worked out with potential master students, to fit the individual interests of the candidates.

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Understanding coevolution: A detailed analysis of coevolution in Daphnia and its microparasites

Evolution does not take place in isolation, but rather within a framework of interacting species. Darwin called this "the tangled bank of nature". While coevolution of complex communities is difficult to understand, science made good progress in understanding how pairs of antagonists coevolve. However, we still lack good examples of well documented cases of specific antagonistic coevolution. Host - parasite interactions are often cited as prime examples for this form of coevolution, but evidence is rather thin. Using field and laboratory research we try to understand the coevolution between Daphnia magna and its parasites. Within this larger project a number of questions are well suited for master projects. The details of projects will be worked out with potential master students, to fit the individual interests of the candidates.

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Understanding species wide diversity

Genetic variation is not random, but well structured. This structure allows us to understand the evolutionary mechanisms at work, shaping the diversity within and between population. We are using the model species Daphnia magna to understand how its tremendous variation come about. For this we collected samples from all over the northern hemisphere and collected data on their phenotypic traits, the ecology of the sites of origin and sequenced their entire genomes. These data enable us to reconstruct the evolutionary history of the species over the last half million years. We discover the signatures of local adaptation, past bottlenecks, migration events and much more. The samples we collected from more than 200 lakes and ponds are kept alive in the laboratory and allow us obtain more data on ecologically relevant phenotypes and combine them with the already known data. Within this larger project a number of questions are well suited for master projects. The details of projects will be worked out with potential master students, to fit the individual interests of the candidates.

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Group: Patrick Tschopp

Plasticity of cell fate decisions in development and evolution

During development, complex tissues and organs are patterned by the correct temporal and spatial specification and assembly of different cell types. We are trying to understand how these processes can change on developmental as well as evolutionary timescales, to pave the way for morphological evolution. In particular, we are interested in how much plasticity there is in the underlying transcriptional control, in response to changes in the embryonic and external environments. As model systems, we are studying the patterning of tetrapod digits and the vertebrate intestine.

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Regulatory evolution during vertebrate skeletogenesis

Every cell of an animal’s body contains (largely) the same genetic information. How then is the enormous diversity of cell types generated during embryogenesis? By differentially regulating a common gene repertoire at the transcriptional level, cell type specification switches get activated to drive progenitor cells towards their eventual cell fate. Studying these processes in different developmental and evolutionary contexts, our work aims to decipher the core underlying regulatory modules as well as their evolutionary flexibility to amend species-specific phenotypes. We use the developing vertebrate skeleton as our model system, for its deep phylogenetic conservation and the well-defined cell types building its basic structure.

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Group: Lukas Schärer

Mechanisms of sexual selection and the evolution of sex allocation

Simultaneous hermaphrodites are male and female at the same time. Individuals therefore need to decide how to distribute limited reproductive resources to their male and female function (e.g. to the production of sperm or eggs). This decision is called sex allocation, and it is an important life history decision in all sexually reproducing organisms. In our earlier work we have shown that the free-living flatworm Macrostomum lignano is a highly suitable model organism to study this question. In this project we will study how different mechanisms of sexual selection, such as sperm competition and cryptic female choice, are important determinants of the evolution of sex allocation, and how these interact with the mating behaviour. The details of project will be worked out with potential master students, to fit the individual interests of the candidates.

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Sexual conflict and the evolution of sperm and genital morphology

In simultaneous hermaphrodites we can expect that individuals often have identical, and therefore incompatible, mating interests (e.g. both individuals may want to give, but not receive sperm). This can lead to a serious conflict of interest over how matings should occur and what should happen to the sperm an individual has received from a partner. These sexual conflicts lead to rapid evolution of sperm and genital morphology. In this project we will study these questions in members the free-living flatworm genus Macrostomum, combining a comparative approach, and experimental work in selected species. The details of project will be worked out with potential master students, to fit the individual interests of the candidates.

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Group: Valentin Amrhein

Ecology, Conservation Biology, Statistics

In this group, we are mostly studying organisms in the field or on the computer. In the past, much work has been done on the song and migration of Nightingales. More recently, we started investigating the effects of natural grazing by Konik horses and Highland cattle in the nature reserve Petite Camargue just north of Basel, where students can live and work at our local research station. Other current projects involve amphibians in the Petite Camargue, or different species of songbirds in the Swiss National Park, in the Val Piora (Ticino) and on the Furka Pass. Large ecological data sets are available for analysis from monitoring programs such as the Biodiversity Monitoring Switzerland. Often, our students work on projects offered by our colleagues at the Swiss Ornithological Institute (Vogelwarte Sempach) or at the environmental consulting company Hintermann & Weber AG. Further, master theses would also be possible on topics related to inferential statistics, science communication, or reproducibility of research.

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Group: Daniel Berner

Mechanisms of adaptive diversification

Understanding adaptive diversification and speciation benefits from integrating information about the selective environments promoting phenotypic diversification on the one hand, and the genomic and developmental variation underlying this diversification on the other hand. While studying the former has been a traditional goal in evolutionary biology, much remains to be learned about the genomic and developmental basis of adaptation. How many genes are under selection when populations diverge ecologically? Are the same genetic variants and developmental pathways used repeatedly when multiple populations adapt to similar habitats? What molecular signatures emerge around genes targeted by selection? How is adaptive genetic variation maintained in natural populations? What are the fitness consequences of genetic differentiation between populations? To shed light on such questions, my group uses threespine stickleback fish and Southern Small White butterflies as empirical research systems. Several investigations are currently running, but opportunities for new projects exist. Expansion to new organismal systems is also welcome.

Genomic and developmental basis of diversification in stickleback fish

Threespine stickleback fish exhibit amazing ecological diversity, and powerful methodological tools have been developed in this species, together making stickleback a classical empirical system for evolutionary genetics. We focus on populations occupying ecologically different habitats and having evolved different life histories, behaviors and morphologies in response to natural selection in Switzerland, Scotland, and Canada. We combine molecular and bioinformatic analysis with field work, theoretical investigations using computer simulations, developmental genetic (evo-devo) experiments, and sometimes manipulative field or mesocosm experiments to shed light on elements of adaptive diversification.

Exploring range expansion in the Southern Small White butterfly

The Southern Small White (Pieris mannii) was initially a locally distributed Mediterranean species, but in the mid 2000s started a spectacular northward expansion across Europe. Our objective is to understand the population history of this invasion, and to explore ecological and genomic factors promoting it. To this end, we combine field work with genomic analyses based on both contemporary and museum samples from across the species’ original and invasive range.

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