Natural genetic variation in cuticular hydrocarbon expression in male and female Drosophila melanogaster

Abstract

Cuticular hydrocarbons (CHCs) act as contact pheromones in Drosophila melanogaster and are an important component of several ecological traits. Segregating genetic variation in the expression of CHCs at the population level in D. melanogaster is likely to be important for mate choice and climatic adaptation; however, this variation has never been characterized. Using a panel of recombinant inbred lines (RILs) derived from a natural population, we found significant between-line variation for nearly all CHCs in both sexes. We identified 25 QTL in females and 15 QTL in males that pleiotropically influence CHC expression. There was no evidence of colocalization of QTL for homologous traits across the sexes, indicating that sexual dimorphism and low intersex genetic correlations between homologous CHCs are a consequence of largely independent genetic control. This is consistent with a pattern of divergent sexual and natural selection between the sexes.

Figure 1.—

Gas chromatograph traces of cuticular hydrocarbons of D. melanogaster for (A) females and (B) males. (A) 1–9:C21; 2–C22; 3–7, 11:C23; 4–9:C23; 5–7:C23; 6–5, 9:C23; 7–5:C23; 8–C23; 9–9, 13:C24; 10–7, 11:C24; 11–9:C24; 12–7:C24; 13–5, 9:C24; 14–5:C24; 15–C24; 16–9,13:C25; 17–7,11:C25; 18–2MeC24; 19–9:C25; 20–6, 10:C25; 21–7:C25; 22–5, 9:C25; 23–5:C25; 24–C:25; 25–9, 13:C26; 26–7, 11:C26; 27–2MeC25; 28–9:C26; 29–7:C26; 30–5, 9:C26; 31–5:C26; 32–C26; 33–9, 13:C27; 34–7, 11:C27; 35–9:C27; 36–2MeC26; 37–7:C27; 38–5, 9:C27; 39–5:C27; 40–C27; 41–9, 13:C28; 42–7, 11:C28; 43–2MeC27; 44–9:C28; 45–C28; 46–9, 13:C29; 47–7, 11:C29; 48–9:C29; 49–7:C29; 50–C29; 51–7, 11:C31; 52–2MeC30; 53–C31. (B) 1–C21; 2–2MeC20; 3–9:C22; 4–7:C22; 5–5, 9:C22; 6–C22; 7–2MeC22; 8–9:C23; 9–7:C23; 10–5, 9:C23; 11–5:C23; 12–C23; 13–9:C24; 14–7:C24; 15–5, 9:C24; 16–C24; 17–2MeC24; 18–7, 11:C25; 19–9:C25; 20–7:C25; 21–5, 9:C25; 22–5:C25; 23–C25; 24–2MeC26; 25–7:C27; 26–C27; 27–2MeC28; 28–C29; 29–2MeC30; 30–2MeC32; 31–C33.

Figure 2.—

Linkage maps of D. melanogaster showing the confidence intervals of individual-trait QTL as estimated by 2-LOD dropdown. The estimated locations of the pleiotropic CHC QTL as determined by CIM in QTL Cartographer are also shown, with confidence intervals estimated by bootstrapping. Likelihood ratio statistic maxima are indicated. The position of markers is noted by a broken line, and cytological positions are provided. A dot on the broken line indicates that a significant association between marker and CHC expression was found in the single-marker analysis.

Figure 2.—

Linkage maps of D. melanogaster showing the confidence intervals of individual-trait QTL as estimated by 2-LOD dropdown. The estimated locations of the pleiotropic CHC QTL as determined by CIM in QTL Cartographer are also shown, with confidence intervals estimated by bootstrapping. Likelihood ratio statistic maxima are indicated. The position of markers is noted by a broken line, and cytological positions are provided. A dot on the broken line indicates that a significant association between marker and CHC expression was found in the single-marker analysis.

Figure 2.—

Linkage maps of D. melanogaster showing the confidence intervals of individual-trait QTL as estimated by 2-LOD dropdown. The estimated locations of the pleiotropic CHC QTL as determined by CIM in QTL Cartographer are also shown, with confidence intervals estimated by bootstrapping. Likelihood ratio statistic maxima are indicated. The position of markers is noted by a broken line, and cytological positions are provided. A dot on the broken line indicates that a significant association between marker and CHC expression was found in the single-marker analysis.

Figure 2.—

Linkage maps of D. melanogaster showing the confidence intervals of individual-trait QTL as estimated by 2-LOD dropdown. The estimated locations of the pleiotropic CHC QTL as determined by CIM in QTL Cartographer are also shown, with confidence intervals estimated by bootstrapping. Likelihood ratio statistic maxima are indicated. The position of markers is noted by a broken line, and cytological positions are provided. A dot on the broken line indicates that a significant association between marker and CHC expression was found in the single-marker analysis.