Genomic insights into the origin of ecotypes

A century ago, Göte Turesson introduced the ecotype concept to describe populations of species that are phenotypically and genetically differentiated by adaptation to contrasting habitats. His simple idea—that ecological divergence can occur below the species level—has had lasting influence, inspiring experimental tests of local adaptation across taxa. Today, ecotypes are described throughout the tree of life and even beyond biology, but their origin and nature remain debated. Genomics has brought new life to Turesson’s concept, revealing variable levels of divergence, complex demographic histories, and a prominent role for pre-existing variation, chromosomal inversions, and gene regulation. These findings refine our understanding of ecotypes and raise new questions about predictability, parallelism, genomic architecture, plasticity and their role in speciation.