Genetical differences in solutions to the crises of hybridization and competition in early sympatry

Abstract

The role of the crises of hybridization and competition in early sympatry is reviewed. Evolutionary rates, coupled with the number of genetic changes and the intensity of selection for them, are generally different for: 1) speciation, i.e. the accumulation of many genetic differences that add up to an irreversible barrier to future fusion; 2) anti-hybridization mechanisms following the establishment of sympatry; and 3) anti-competition mechanisms that allow related species to share the same geographical range with minimal competition for food. In new contacts the unrelated crises of hybridization and resource competition seem likely to be solved in different styles, because cross-mating is commonly stopped by very few genetic changes, whereas niche-splitting typically involves many more changes. These statements — correct as broad generalization — are documented by many examples, mostly from Lepidoptera (Eds.). © 1985 Taylor & Francis Group, LLC.