Urban enrichment of molestus ancestry and opposing temperature clines in a metropolitan Culex pipiens hybrid zone

In a Baltimore–Washington Culex pipiens hybrid zone, molestus-like ancestry increases with impervious surface, while temperature shifts ancestry in opposite directions at specific loci, including a chromosome 3 inversion.

• Why it matters: Hybridization can spread locally favored alleles, but how urbanization and temperature jointly shape introgression in a major West Nile virus vector remains unclear.
• What they did: Whole-genome Pool-seq from 24 field populations and three lineage-reference pools tested genome-wide ancestry patterns across intersecting temperature and urbanization gradients.
• The result: Molestus-like ancestry rises with impervious surface independently of temperature, an 11.6 Mb chromosome 3 inversion tracks molestus-like ancestry, and temperature acts locus by locus, including CYP6 paralogs on chromosome 1 and a Yan-centered interval on chromosome 2.

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