Earlier in summer, there was a gigantic 4-year longitudinal study in France showing that the school environment triggers a gender gap in mathematics. www.nature.com/articles/s41...

One more surprise! W/ @egorlappo.me , we showed these rapid and large frequency changes of the resistant Ace drove a chromosome-scale sweep during insecticide selection and a reverse sweep after reversal of selection. Fluctuating selection's footprints extend far beyond the target! 16/n

@alyulina.bsky.social 's modeling revealed the smoking gun: low fitness costs & low dominance are required to explain the resistant Ace allele dynamics in both treated and untreated populations—confirming recessive costs! 14/n

The resistant Ace alleles and resistance rapidly increase during insecticide treatment, then decline after insecticide selection reversal —but they persisted at low frequency without insecticides. The pattern suggested recessive costs hidden in heterozygotes! 13/n

From Jun to Dec 2021, we tracked genome-wide allele frequencies and resistance with and without a seasonal insecticide pulse every ~1-2 generations. @andyvhuynh.bsky.social 's population analyses revealed our first surprise. The insecticide pulse didn't suppress the treated populations! 11/n

Perfect timing— @markcbitter.bsky.social adaptive tracking study (Bitter et al., Nature, 2024) had a set of untreated mesocosms running. Adding another set of treated mesocosms created a powerful test for beneficial dominance reversal! 10/n

The lab results were exciting! The resistance benefits of Ace alleles are dominant with malathion, while some fitness costs are recessive (or codominant) in its absence. But lab phenotyping has limits. Which traits really matter in nature? 8/n

We first tested for dominance of the resistant Ace alleles in the lab! With amazing undergrad Zach Mouza, we created all Ace genotype combinations using a panel of inbred lines from Paul Schmidt lab and measured fitness-related traits with and without the organophosphate malathion 7/n

Using 20 years of population genomic data from the DEST consortium & pesticide use data from FAOSTAT, we found that the resistant Ace alleles persist worldwide, and their frequency responds to selection but neither fix nor disappear. Exactly the pattern we were trying to explain! 6/n

We tested this idea with insecticide resistance. Living closely with us, fruit flies have evolved resistance to widely-used organophosphates through large-effect resistant alleles at the Ace locus—their molecular target. Ideal genetic system to study how variants persist! 5/n