Linked song and preference loci suggests substantial contribution of genetic coupling in rapid speciation of the <i>Laupala</i> crickets

Signals and preferences are central to the evolutionary origins and maintenance of reproductive barriers between species. How such communication systems evolve is key to understanding speciation. One central question considers how signals and preferences coevolve as lineages diverge. Here, we study the rapidly speciating Laupala crickets, a system characterized by coordinated sexual signaling and acoustic barriers to gene flow between species. By mapping a new locus underlying female song preference as well as fine-mapping a locus for male pulse rate of the acoustic communication system, we examine the genetic architecture underlying signal-preference divergence. We document a pair of colocalizing pulse rate and preference QTL on linkage group 4, with peak locations less than 2 cM apart, offering strong evidence for genetic coupling. Intriguingly, this is the third pair of colocalizing male and female loci mapped in the Laupala genome. The cumulative effect size of the three pairs of colocalizing loci account for roughly half of the interspecific difference, suggesting that genetic coupling has contributed substantially to the evolution of this behavioral barrier in Laupala. Annotation of the QTL region identified numerous functionally relevant candidate genes, including acetylcholinesterase (AChE) and ryanodine receptor (RyR).