Intralocus sexual conflict and insecticide resistance

Area of Science:

• Evolutionary genetics
• Insecticide resistance mechanisms
• Drosophila melanogaster research

Background:

• The BA allele of the Drosophila cytochrome P450 gene Cyp6g1 confers insecticide resistance.
• This allele can cause intralocus sexual conflict, benefiting females but harming males, particularly in older genetic backgrounds.
• It remains unclear if these sexually antagonistic effects persist in modern populations that have evolved alongside insecticides.

Purpose of the Study:

• To investigate sexually antagonistic fitness effects of the BA allele in contemporary Drosophila melanogaster populations.
• To determine if genetic modifiers have evolved to offset male fitness costs in insecticide-evolved populations.
• To explore the population-level implications of insecticide resistance and sexual conflict.

Main Methods:

• Analysis of Drosophila melanogaster recently collected from an Australian population.
• Fitness assays to evaluate the effects of the BA allele on male and female reproductive success.
• Experimental evolution to assess long-term selection dynamics at the Cyp6g1 locus.

Main Results:

• Increased fecundity observed in insecticide-resistant BA females.
• No consistent evidence of male fitness costs was found at the individual level.
• Experimental evolution revealed balancing selection at the Cyp6g1 locus.

Conclusions:

• Sexually antagonistic fitness effects of the BA allele may not be apparent at the individual level in current populations.
• Reduced reproductive investment in resistant males might explain the lack of observed male fitness costs.
• Population-level dynamics, rather than individual assays, are crucial for understanding complex sexually antagonistic fitness effects.