No Evidence of Sexually Antagonistic Coevolution in Drosophila Reproductive Tract Transcriptomes

Area of Science:

• Evolutionary biology
• Genomics
• Animal behavior

Background:

• Drosophila seminal fluid proteins (SFPs) are a model for interlocus sexual conflict.
• SFPs increase male fitness but decrease female fitness, driving counter-adaptations and rapid evolution.
• Sexual conflict predicts male genetic variation in SFPs should lead to coevolving female genetic pathways.

Purpose of the Study:

• To test for sexual coevolution in female post-mating gene expression in Drosophila melanogaster.
• To investigate if male SFP expression divergence drives female counter-adaptations.
• To explore alternative hypotheses for population differentiation in female transcriptomes.

Main Methods:

• Comparative transcriptomics of three D. melanogaster populations with divergent SFP expression.
• Analysis of female post-mating gene expression in reproductive tract and head tissues.
• Contrasting gene expression patterns against predictions of sexual antagonism and environmental selection.

Main Results:

• Female post-mating gene expression was independent of the male population of origin.
• No evidence of female counter-adaptations driven by male SFP variation was found.
• Population differentiation in female transcriptomes is better explained by female genotypic variation.

Conclusions:

• The study challenges the interlocus sexual conflict model for SFP evolution in these populations.
• Environmental variation is a more likely source of selection on male SFP expression.
• Female-specific genotypic differences are key drivers of female post-mating transcriptome differentiation.