Do Males Matter? Exploring Male-Mediated Effects on Female Meiotic Recombination. Chad M. Hunter, Nadia Singh. Department of Genetics, North Carolina State University, Raleigh, NC 27695.

   Homologous recombination is a critical genetic process as well as a driving evolutionary force. Rates of crossing-over are highly variable within and between species due to both genetic and environmental factors. Early studies in Drosophila implicated female genetic background as a major determinant of recombination rate and recent work has highlighted male genetic background as a possible mediator as well. This latter result was puzzling since Drosophila males do not undergo meiotic recombination. We used classical genetics to address the question of how maternal and paternal genetic background affect crossover rate. We devised a two-step crossing scheme exploiting visible markers to measure rates of crossing over in a 33 cM region of the D. melanogaster X chromosome. In total, we measured crossover rates in females from ten inbred lines crossed to males from each of the same ten inbred lines. Our experimental design facilitates measuring the contributions of female genetic background, male genetic background, and male by female interaction effects on rates of crossing-over in females. Our results indicate that paternal genotypes do not significantly affect female meiotic crossover rates in Drosophila and that instead, maternal genotypes explain the majority of the observed variation in crossover rate. Our results have implications for deciphering the molecular and genetic basis of recombination rate variation in Drosophila.