Genetic background effects on meiotic recombination.

Genetic background is a strong driver of phenotype, and when analyzing a mutant phenotype, it is critical that a genetically comparable wildtype stock is used as a control. Many of the Drosophila melanogaster meiotic mutants were isolated in EMS screens or created by P-element mutagenesis and do not have a congenic or isogenic wildtype control. We show here that the y (1) stock, commonly used for transgenesis in D. melanogaster , shows significantly higher meiotic crossover rates, and there is likely a modifier of meiosis or germline development in the genetic background of this popular stock.