Two PhD positions in Ecological Genetics of Speciation and Hybridization in African cichlid fish ~

13 de septiembre de 2004

Two PhD positions in Ecological Genetics of Speciation and Hybridization in African cichlid fish

Two 3-years PhD projects are available in the research group of Ole Seehausen in both the Aquatic Ecology section of the Institute of Zoology, University of Bern, Switzerland and the Limnological Research Centre of the EAWAG, Kastanienbaum, Switzerland, to investigate using African cichlid fish, (a) the role of different types of selection during speciation-with-geneflow, (b) the role of hybridization in generating adaptive novelty,. One of the least well understood problems in evolutionary biology and biodiversity research is why some organisms have undergone massive speciation and adaptive diversification in very short time, whereas many others, often closely related and superficially similar, have not. Variation in the propensity to speciation with geneflow, driven by ecological processes that exert disruptive or diversifying selection is now receiving a lot of attention, and an intensive debate centres on possible causes of disruptive selection during such speciation. Diverging mating preferences are assumed in many of the models, and in most speciation scenarios for cichlids. However, it is unclear whether such divergence of mating preferences is recruited by selection resulting from competition for ecological resources or by selection resulting from competition for mating opportunities, followed by ecological character displacement.
One PhD project ('speciation project') will aim at developing experimental tests of predictions made by alternative speciation models with regard to the emergence of gene associations and genetic linkage groups comprising alternative sets of genes. We will use hybridizing morphs or incipient species of Lake Victoria cichlids to (i) subject different classes of traits to tests of disruptive selection, and (ii) to identify chromosomal linkage groups containing "speciation traits" by association scans with AFLP markers. Another unresolved problem associated with the rapid emergence of adaptive diversity is the source of genetic variation that endows some lineages with unusually high rates of phenotypic evolution. One idea is that hybridization in novel environments between genetically well differentiated lineages endows resulting hybrid populations with large variation in quantitative traits that allow them subsequently to radiate in response to diversifying selection. The second PhD project ('hybridisation project') will use experimental ecological genetics to test predictions of this hypothesis. This involves experimental quantification of morphological diversity generated by interspecific hybridization and experimental parameterisation of endogenous and ecological hybrid fitness and functional hybrid diversity in relation to genomic and ecological distinctiveness of parental species. We will work with cichlid fish species that we have recently identified as likely ancestors of several African radiations. We are looking for enthusiastic, dedicated students with a master's degree or equivalent (e.g. Diplom) in Biology and background in evolutionary theory and population genetics or quantitative morphometrics. The speciation project will involve a large amount of work in our molecular laboratory, extracting DNA, PCR, fragment separation on automated sequencers, genetic data analysis, but considerable amounts of morphometric and ecological work, fieldwork on Lake Victoria, and possibly experimental fish breeding too. The hybridization project involves breeding and hybridization experiments in our new purpose built fish house on Lake Lucerne, quantification of shape using geometric morphometrics, quantification of colour and behaviour, molecular genetic work using AFLPs, and some fieldwork to collect cichlids. Some experience in the generation and analysis of molecular genetic data will be required for the speciation project, and will be advantagous for the hybridization project too. Experience with quantitative morphometric data analysis and quantitative genetics will be advantageous, as will be experience with handling and maintaining life fish. The successful applicants will be able to work independently, as well as in small teams. They will collaborate closely with postdoctoral researchers in our research group. Further, they will interact with the large community of population biologists, ecologists and geneticists at the Institute of Zoology (
and the population and system ecologists at the Limnological Research Centre (
Besides research, PhD students are expected to contribute to undergraduate teaching and supervision (teaching load not exceeding 10 percent of working time). Salaries will be according to Swiss National Science Foundation (SNF) salary schemes. Closing date is the 24th of September 2004. Starting date could be as soon as the 1st of October 2004 and should be no later than the 30th of November 2004. Please send application (preferably by E-Mail) with CV, summary of past research experience, and contact details of two referees to the secretary's office: Susanne Maurer, Dept. of Aquatic Ecology, Institute of Zoology, University of Bern, Baltzerstr. 6, CH-3012 Bern, Switzerland; or as an e-mail attachment to Please send copies of e-mail attachments to For inquiries please contact: Please specify which project you are interested in, or whether you want to be considered for either.

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