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Digest: Chance and necessity shape introgression patterns across three replicate avian hybrid zones
1Wildlife Ecology and Conservation, Wageningen University, the Netherlands.
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Predicting evolutionary outcomes remains a central challenge in biology. Using three replicate hybrid zones in the Western Andes of Colombia, Castaño et al. (2026) assessed the repeatability of introgression between Lemon-rumped and Flame-rumped Tanagers. Genomic cline analyses revealed heterogeneous patterns of neutral introgression, but deterministic introgression at a plumage-associated locus on chromosome 22. Together, these patterns show that introgression reflects a balance of chance and necessity, with selection generating predictable outcomes amid substantial genomic contingency.
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