GEE Seminar - Professor Simon Myers, University of Oxford

Academic Host: Garrett Hellenthal
Abstract: In mammals, hybrids are often infertile, and this is thought to be a key driver of species formation – but how does this happen? In mammals, only a single speciation gene has so far been identified, in mice. In this talk I will talk about how this sterility is deeply connected to recombination, which shuffles mutations into new combinations, and to the pairing of chromosomes, essential to ensure one of each pair is passed on to offspring, two fundamental processes which are very incompletely understood. I will describe our collaborative work that has revealed how specific DNA sequences, which differ between all species so far examined, “code” for possible recombination sites, and identified key genes involved. Remarkably, simply modifying this code fully reverses hybrid sterility, in several cases.

Evolution of this code occurs extraordinarily rapidly both in cis and in trans, driving diverse phenomena: it explains hybrid sterility in mice, the origins of many human diseases, and why different human populations have differing recombination landscapes. The study of hybrid mice has led to an improved understanding of an enduring biological mystery: how do homologous chromosomes precisely align, finding their exact partners among billions of genetic bases of DNA within the cell? We speculate that this explains why, in most studied species, recombination occurs in only a tiny fraction of the genome, in “hotspots”, and discuss a range of evolutionary implications.