Quantitative Trait Loci for Sexual Isolation Between Drosophila simulans and D. mauritiana

Abstract

Sexual isolating mechanisms that act before fertilization are often considered the most important genetic barriers leading to speciation in animals. While recent progress has been made toward understanding the genetic basis of the postzygotic isolating mechanisms of hybrid sterility and inviability, little is known about the genetic basis of prezygotic sexual isolation. Here, we map quantitative trait loci (QTL) contributing to prezygotic reproductive isolation between the sibling species Drosophila simulans and D. mauritiana. We mapped at least seven QTL affecting discrimination of D. mauritiana females against D. simulans males, three QTL affecting D. simulans male traits against which D. mauritiana females discriminate, and six QTL affecting D. mauritiana male traits against which D. simulans females discriminate. QTL affecting sexual isolation act additively, are largely different in males and females, and are not disproportionately concentrated on the X chromosome: The QTL of greatest effect are located on chromosome 3. Unlike the genetic components of postzygotic isolation, the loci for prezygotic isolation do not interact epistatically. The observation of a few QTL with moderate to large effects will facilitate positional cloning of genes underlying sexual isolation.

Linkage of butterfly mate preference and wing color preference cue at the genomic location ofwingless

“…In general there is little reason to expect that the same gene or suite of genes would influence both a morphological trait used in mate recognition and the sensory processes used to recognize that trait (12,41,42). In fact, outside of the recent demonstration that the gene desat1 influences both production and discrimination of sex pheromones in Drosophila melanogaster (43), there is no experimental evidence to support such ''genetic coupling'' in mate recognition.…”

Genetics and genomics of Drosophila mating behavior

“…Two recent studies addressed the genetic basis of variation in sexual isolation between Drosophila pseudoobscura and Drosophila persimilis (61) and between Drosophila simulans and Drosophila mauritiana (62) by linkage to molecular markers in large backcross populations. In the first species pair, sexual isolation is attributable to female discrimination against males of the sibling species; males readily court females of either species.…”

Expression of a desaturase gene,desat1, in neural and nonneural tissues separately affects perception and emission of sex pheromones inDrosophila

“…The genetic control of the signal and its reception must be tightly coadapted, especially in interindividual sexual communication to ensure sexual isolation (1)(2)(3). However, the basic genetic architecture of prezygotic sexual isolation remains largely unexplored in most natural populations (4,5), and there is very little empirical evidence for tight genetic linkage between the emission and reception of a sensory signal (6)(7)(8)(9). Theoritical prediction and experimental studies assume that the "emission/reception coupling" depends on the inheritance of separate genes found on the same or on different chromosomes and linked with a high probability (linkage desequilibrium (10)(11)(12)(13)(14), whereas the "single-gene" hypothesis seems very unlikely (4), as the tissues involved in the emission and perception of sensory signals are usually different (15).…”