Character displacement

Character Displacement

Illustration of character displacement in two species.

Character displacement is an evolutionary phenomenon where differences among similar species whose distributions overlap geographically are accentuated in regions where the species co-occur, but are minimized or lost where the species' distributions do not overlap. This pattern results from evolutionary changes driven by competition between species for limited resources.

Mechanism

Character displacement occurs when two species compete for the same resources. In areas where their ranges overlap, natural selection favors individuals in each species that use different resources, thereby reducing competition. Over time, this can lead to morphological, behavioral, or ecological changes that reduce niche overlap between the species.

Types of Character Displacement

Character displacement can be categorized into two main types:

• Ecological Character Displacement: This involves changes in traits that affect the ecological niche of a species, such as changes in feeding behavior or habitat preference.
• Reproductive Character Displacement: This involves changes in traits that affect reproductive interactions, such as changes in mating calls or timing of reproduction, which reduce hybridization between species.

Examples

A classic example of character displacement is seen in Darwin's finches on the Galápagos Islands. Different species of finches have evolved distinct beak shapes and sizes that allow them to exploit different food resources, reducing competition among them.

Another example is found in anole lizards in the Caribbean, where different species have evolved variations in limb length and body size that allow them to occupy different ecological niches.

Importance in Evolution

Character displacement is an important concept in evolutionary biology because it illustrates how competition can drive speciation and the diversification of life. It provides evidence for the role of natural selection in shaping the traits of organisms and the structure of ecological communities.

Related Pages

• Natural selection
• Speciation
• Ecological niche
• Darwin's finches
• Anole lizards