Practice question

Character displacement produces divergence in heritable traits where ecologically similar species coexist. Competition makes phenotypes that rely less on the shared limiting resource relatively advantageous, so natural selection shifts trait distributions apart over generations. As morphology, behavior, or phenology diverges, resource-use overlap declines. Greater similarity or increased overlap would intensify competition and oppose the selective direction. Habitat size need not change; the species differentiate within the available environment. A convincing case requires more than sympatric differences: trait divergence should exceed that found in allopatry, traits should affect resource use or reproductive interaction, and alternative environmental explanations should be excluded. Ecological character displacement concerns resource competition, while reproductive character displacement reduces costly mating interactions or hybridization. The result may facilitate coexistence, but it is contingent on genetic variation and accessible alternative resources. Short-term behavioral narrowing without inherited change is ecological compression, not character displacement. Reduced niche overlap is therefore the functional consequence that connects evolutionary trait divergence to weaker interspecific competition.