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Genetic basis of reproductive isolation: variation across species

Research unit

UMR 7156 - Génétique Moléculaire, Génomique et Microbiologie (GMGM)
Institut de physiologie et de la chimie biologique (IPCB) 21 rue René Descartes 67084 Strasbourg Cedex

Group

Name: Variation intraspécifique et évolution des génomes

Group leader: SCHACHERER Joseph - schacherer@unistra.fr

Group leader's phone: 0368851961

Website: Visit website

Group organization:
- Chercheurs: 5
- ITA: 2
- Doctorants: 4
- Post-Docs: 2
- Autres: 2

Publications of the team linked to the topic (3 last years):
1) Friedrich A, Jung P, Reisser C, Fischer G, Schacherer J. Population genomics reveals chromosome-scale heterogeneous evolution in a protoploid yeast. Mol Biol Evol. 2015. 32:184-92.
2) Hou J, Friedrich A, de Montigny J, Schacherer J. Chromosomal rearrangements as a major mechanism in the onset of reproductive isolation in Saccharomyces cerevisiae. Curr Biol. 2014. 24(10):1153-9.
3) Freel KC, Friedrich A, Hou J, Schacherer J. Population genomic analysis reveals highly conserved mitochondrial genomes in the yeast species Lachancea thermotolerans. Genome Biol Evol. 2014. 6:2586-94.

About PhD

PhD Director: DE MONTIGNY Jacky - montigny@unistra.fr

Phone: 0368852023

Junior advisor: non

Co-tutely: non

Co-Director: SCHACHERER Joseph
University of Co-Director: Université de Strasbourg

About PhD topic :

Title: Genetic basis of reproductive isolation: variation across species

Project: Identification of the genetic variation within and between species is valuable for understanding the genetic basis of phenotypic differences and therefore the patterns of molecular evolution. Genome evolution is largely connected with different types of chromosomal rearrangements such as deletions, translocations, duplications and point mutations as well. These genetic variants are key factors in evolutionary processes because they promote genomic plasticity. In addition, these variants can lead to reproductive isolation i.e. to the partial or complete decrease of the offspring viability. This latest process might be considered as a first step towards speciation.

The characterization of genetic variants involved in reproductive isolation is therefore crucial to have a better understanding of the mechanisms leading to new species. In this context, the Saccharomycotina yeasts represent an ideal group of organisms. Due to their genome size and currently available tools, the genetic basis of reproductive isolation is more readily identified and thoroughly characterized in S. cerevisiae than in higher eukaryotes. Between S. cerevisiae and its sibling species of the Saccharomyces complex, reproductive isolation acts postzygotically and could be attributed to chromosomal rearrangements, cytonuclear incompatibility, and antirecombination. More recently, intraspecific reproductive isolation was identified within species and more precisely in S. cerevisiae. Chromosomal rearrangements were found to be a major mechanism in the onset of reproductive isolation. However, the genetic diversity in S. cerevisiae (~1%) is low compared to other Saccharomycotina species (~2-4%) and it might not be representative.

Hence, the aim of this project will be to dissect the genetic origin in a species not closely related to the Saccharomyces genus and showing a higher genetic diversity. We decided to focus on the Lachancea kluyveri species showing up to ~2.5% of genetic polymorphism and for which we already performed a population genomic study. The project will focus on two objectives:
(i) first, the goal will be to identify cases of reproductive isolation by crossing a large number of natural isolates and following the offspring viability. A preliminary study already identifies some cases of isolation.
(ii) second, the aim will be to identify the genetic mechanisms involved in the identified reproductive isolation cases. This will help us to know what kind of mechanisms are involved as well as if the mechanisms are conserved or not across species from the same subphylum.

Successful development of this project will give a global view of the mechanisms leading to reproductive isolation across a large evolutionary scale: the Saccharomycotina subphylum.

Wished skills: Theoretical and practical knowledge of yeast genetics, molecular biology and functionnal genomics. Practical experience of microbiological methods.

Expertises which will be acquired during the training: Fundamental domains: dynamics and evolution of genomes, whole-genome analysis, in silico approaches: phylogeny, evolution and speciation.
Methodological domains: yeast biology, molecular biology, deep sequencing analysis.