BioProject

The number of crossovers and their location across genomes are highly regulated during meiosis, yet these key processes are fast evolving, hindering our understanding of the mechanistic causes and evolutionary consequences of changes in crossover control. More...

The number of crossovers and their location across genomes are highly regulated during meiosis, yet these key processes are fast evolving, hindering our understanding of the mechanistic causes and evolutionary consequences of changes in crossover control. Drosophila melanogaster has been a model species to study meiosis for more than a century, with an available high-resolution crossover map that is, nonetheless, missing for closely related species, thus preventing evolutionary context. Here, we applied a novel and highly efficient approach to generate whole-genome high-resolution crossover maps in D. yakuba to tackle multiple question that benefit from being addressed collectively within an appropriate phylogenetic framework, in our case the D. melanogaster subgroup. The genotyping of more than 1,600 individual meiotic events allowed us to identify several key distinct properties relative to D. melanogaster. We show that together with higher crossover rates than D. melanogaster, D. yakuba has a stronger centromere effect and stronger crossover assurance than any Drosohila species analyzed to date. We also report the presence of an active crossover-associated meiotic drive mechanism for the X chromosome that results in the preferential inclusion in oocytes of chromatids with crossovers under benign conditions. Our evolutionary and genomic analyses suggest that the genome wide landscape of crossover rates in D. yakuba has been fairly stable and captures a significant signal of the ancestral crossover landscape fr the whole D. melanogaster subgroup, even informative for the D. melanogaster lineage. Contemporary crossover rates in D. melanogaster, on the other hand, do not recapitulate ancestral crossover landscapes. As a result, the temporal stability of crossover landscapes observed in D. yakuba makes this species an ideal system for applying population genetic models of selection and linkage, given that these models assume temporal constancy in linkage effects. Our study emphasizes the importance of generating multiple high-resolution crossover rate maps within a coherent phylogenetic context to broaden our understanding of crossover control during meiosis and to improve studies on the evolutionary consequences of variable crossover rates across genomes and time. Less...