The causes and consequences of sex-differences in recombination rates and landscapes.

Meiotic recombination is a fundamental feature of sexual reproduction with great evolutionary importance. Its molecular mechanisms are remarkably conserved, yet its rates and distribution along chromosomes are hugely variable across eukaryotes. Understanding this diversity remains a major challenge in evolutionary biology. Individual sex is a major source of variation in autosomal recombination. This “heterochiasmy” can differ in direction and strength within and between closely related species, chromosomes, and genomic regions. Understanding its causes and consequences has direct importance for evolutionary and molecular biology, yet how and why heterochiasmy has evolved remains unknown. A major barrier is that evolutionary studies rarely consider that recombination occurs in distinct cellular processes (oogenesis vs. spermatogenesis), with striking sex-differences in its underlying genetic basis, genome structure, and fitness impacts. Therefore, understanding the causes and consequences of heterochiasmy is a crucial step to understanding the evolution of recombination itself.RECOSEX will be the first study to explicitly test hypotheses of heterochiasmy evolution. Our newly established model of recombination, the house sparrow, provides an unparalleled opportunity to link genetic variation, molecular function, and selection on heterochiasmy in a natural population. My team will capitalise on rapidly developing “multi-omic” technologies to reveal (i) the sequence-level landscape of heterochiasmy and its genomic and functional basis, (ii) fitness consequences and selection on recombination in both sexes, and (iii) the evolutionary dynamics of heterochiasmy across Passerine birds. RECOSEX will give new and comprehensive insights into a fundamental biological process directly associated with genetic inheritance and reproductive success, and will transform our understanding of how and why the huge diversity of recombination both within and between species has evolved.