Digest: population-level processes that facilitate divergence differ between Andean and Amazonian birds

Wacker and Winger (2026) examine population-level divergence across two very different but connected landscapes, the Andes and the Amazon, using genomic data from eight Tangara bird species. Andean populations show strong genetic structure, with lower gene flow and genetic diversity. In the Amazon, genetic structure is weak, with higher gene flow and genetic diversity. These results suggest that divergence can happen more easily in the Andes due to stronger geoclimatic barriers than in lowland Amazonia.