Natural Variation in the Strength and Direction of Male Mating Preferences for Female Pheromones in <i>Drosophila melanogaster</i>

<div><p>Many animal species communicate using chemical signals. In <i>Drosophila</i>, cuticular hydrocarbons (CHCs) are involved in species and sexual identification, and have long been thought to act as stimulatory pheromones as well. However, a previous study reported that <i>D. melanogaster</i> males were more attracted to females that were lacking CHCs. This surprising result is consistent with several evolutionary hypotheses but is at odds with other work demonstrating that female CHCs are attractive to males. Here, we investigated natural variation in male preferences for female pheromones using transgenic flies that cannot produce CHCs. By perfuming females with CHCs and performing mate choice tests, we found that some male genotypes prefer females with pheromones, some have no apparent preference, and at least one male genotype prefers females without pheromones. This variation provides an excellent opportunity to further investigate the mechanistic causes and evolutionary implications of divergent pheromone preferences in <i>D. melanogaster</i> males.</p></div

Preferences of <i>D. simulans</i> males.

<p>Mean courtship indices for <i>D. simulans</i> males when paired with: <i>D. simulans</i> females, oe⁻<i>D. melanogaster</i> females (lacking CHCs), oe⁺<i>D. melanogaster</i> females (expressing CHCs), sham-perfumed oe⁻ females and oe⁻ females perfumed with <i>D. melanogaster</i> female CHCs. Error bars indicate standard errors, and columns labeled with different letters are significantly different from one another (pairwise Wilcoxon tests followed by sequential Bonferroni adjustment, p<0.05). N = 15–30.</p

Preference variation in <i>D. melanogaster</i> males.

<p>Preference indices for <i>D. melanogaster</i> males from 12 inbred genotypes and one outbred population (allRAL) when allowed to choose between perfumed oe⁻ females and sham-perfumed oe⁻ females (lacking CHCs). The preference index is the relative advantage of oe⁻ females over perfumed females, such that positive values indicate a preference for females lacking CHCs. Asterisks above the columns show preference indices that are significantly different from 0 (binomial tests: * p<0.05; ** p<0.01 and significant after sequential Bonferroni adjustment). N (Canton-S)  = 94, all other n = 26–60.</p