The evolution of recombination rates

• Applicant: Dr. Bart Nieuwenhuis
• Subject Area: Evolution and Systematics of Plants and Fungi ; General Genetics and Functional Genome Biology ; Evolution, Anthropology
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 427888028

Recombination is a key driver of evolution by generating variation. It facilitates adaptive evolution by bringing together beneficial allele combinations, but can equally impede adaptation, by breaking up such beneficial combinations. These opposing effects reflect themselves in the variation of recombination that exists between species, populations, individuals, and even regions of the genome, so-called recombination hotspots and coldspots. Recent genomic studies have shown how common this variation is, but the role of this variation in evolution is largely unknown. We need to study recombination as an independent trait by understanding its variation and heritability to understand how variation in recombination can affect evolutionary processes, such as adaptation and maintenance of genetic variation.I have recently developed a high-throughput method that uses direct selection on haploid recombinant offspring for experimental evolution in fission yeast – a well-established model for functional studies on meiosis. I will use this setup, together with analyses of natural variation in fission yeast, to study the trait recombination rate and the genetics underlying this rate. In this project, we aim to 1) describe natural variation in recombination rates, 2) measure heritability of recombination rates in natural variation, 3) define constraints on recombination rates and 4) identify regulatory mechanisms affecting local and global recombination rates.The extensive knowledge on fission yeast meiosis makes this an excellent system to study the mechanisms underlying recombination-rate modifications. I will analyze the natural variation for recombination rates along the genome and between genotypes, making use of a large collection of available strains using an efficient method to measure recombination between many linked loci. Heritability of rates will be studied in the haploid recombinant offspring that will be genotyped and used for a genome-wide association study to find candidates for recombination rate variation. Experimental evolution of fission yeast will be used to select for increased or reduced recombination rates at local and genome wide levels, in 96 lines under four different scenarios. Candidate genes from the association study and mutations evolved during experimental evolution will be tested for their effects. The proposed approach will show the heritability of recombination rate and its variation in nature, and the limitations to recombination rate change. This project will transform our insights into the mechanisms and heritability of recombination rate variation, gaining essential knowledge towards understanding its effect on fitness and its role in evolution.

• DFG Programme: Research Grants