Abstract
Connecting genetic variation to trait variation is a grand challenge in biology. Natural populations contain a vast reservoir of fascinating and potentially useful variation, but it is unclear if the causal alleles will generally have large enough effects for us to detect. Without knowing the effect sizes or allele frequency of typical variants, it is also unclear what methods will be most successful. Here, we use a multi-parent advanced intercross population (the Drosophila Synthetic Population Resource) to map natural variation in Drosophila courtship song traits. Most additive genetic variation in this population can be explained by a modest number of highly resolved QTL. Mapped QTL are universally multiallelic, suggesting that individual genes are “hotspots” of natural variation due to a small target size for major mutations and/or filtering of variation by positive or negative selection. Using quantitative complementation in randomized genetic backgrounds, we provide evidence that one causal allele is harbored in the gene Fhos, making this one of the few genes associated with behavioral variation in any taxon.
