Research Fellows Directory
Dr Susan Johnston
University of Edinburgh
When an individual produces eggs or sperm, the chromosomes inherited from its mother and father will swap large chunks of DNA in a process known as recombination, creating new chromosomes that are a mosaic of genetic material from each parent. Recombination is an important source of genetic diversity, as it generates new combinations of genes that can be favoured or purged by natural selection. The rate of recombination must strike a fine balance between its costs and benefits: too little recombination can lead to mistakes in chromosome number, a leading cause of miscarriage; too much recombination can cause harmful mutations and break up favourable combinations of genes built up by selection. The optimal rate of recombination is likely to vary under different strengths of selection, meaning that recombination rate itself may be subject to selection and evolving over time. Understanding this evolution has applications in medical genetics, sustainable animal and plant breeding, and evolutionary rescue of vulnerable populations. However, our understanding of its evolution has been limited by suitable genomic data to test key hypotheses. My research addresses knowledge gaps in this field by using new genomic technologies to identify the genes controlling recombination rate in natural and domestic populations of sheep, cattle, deer and sparrows. I aim to link variation in these genes to the survival and reproductive success of individuals and their offspring, to determine which level of recombination leads to the highest quality offspring - or if there are hidden causes or consequences of rate variation that we have not yet discovered. In addition, I use both theoretical and empirical approaches to determine if variation in where recombination occurs on individual chromosomes can have a selective advantage in wild and domesticated mammal populations. Overall, my research works towards predicting how recombination will affect responses to selection in our changing world.
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