Dispersal

Definition

The movement of individuals away from their birthplace, parental aggregation, or current population center, resulting in gene flow, range expansion, or colonization of new habitat. In arthropods, dispersal encompasses active locomotion (walking, flying, swimming) and passive transport by wind, water, or phoresy on other organisms. It is distinguished from migration by lacking a return phase and from foraging by its directional bias away from high-density areas.

Etymology

Latin dispergere, to scatter widely

Example

Aphids produce winged morphs specifically for dispersal; when crowding triggers this polyphenism, alates fly to distant host plants, founding new colonies and reducing intraspecific competition.

Synonyms

• Emigration
• dissemination

Related Terms

• Migration
• Gene flow
• range expansion
• Colonization
• Phoresy
• ballooning
• Population dynamics
• metapopulation
• invasion biology

Usage Notes

Ecologists distinguish natal dispersal (first movement from birthplace) from breeding dispersal (movement between breeding sites). Passive dispersal (anemochory, hydrochory, zoochory) is particularly important for small arthropods with limited active range. The term implies net movement away from aggregation; random or undirected movement without density-dependent departure is better described as diffusion or exploratory behavior.