The Adaptive Landscape as a metaphor of Fitness

In a two-dimensional landscape of Fitness vs Genotype-based Phenotypes, certain combinations produce phenotypes that are well-adapted for local circumstances. Speciation may occur when a genotype is selected from one adaptive peak to another, nearby in in genotype-phenotype space. In Sewall Wright's model, this requires transition through a mal-adapative combination, which is possible in small populations where genetic drift predominates natural selection.