Dispersal

Dispersal is the movement of organisms or propagules away from their origin or from areas of high population density. It differs from migration in that dispersal is typically non-seasonal, not undertaken for a return path, and often involves the establishment of a new territory or lineage. Dispersal can occur at various life stages and can involve individuals, gametes, seeds, spores, or genetic material.

Dispersal is categorized by mode: active or passive. Active dispersal is movement under the organism's own power (e.g., many animals, some plants via growth; for plants, wind or water dispersal may be considered passive). Passive dispersal relies on external agents such as wind (anemochory), water (hydrochory), or animals (zoochory, including ingestion, attachment, or caching). Other mechanisms include ballistic dispersal in plants and gravity (barochory).

Dispersal influences population structure, gene flow, colonization of new habitats, metapopulation dynamics, and responses to fragmentation and climate change. Dispersal distance is often described by a dispersal kernel, a probability distribution of distances moved. Dispersal can be limited by landscape features, barriers, and behavioral or physiological traits. Human activities can alter dispersal by habitat modification, fragmentation, and species introductions, with consequences for invasive species and restoration ecology.

In plants, seed dispersal shapes species distributions, genetic diversity, and community assembly. In animals, juvenile dispersal affects life history and mating systems. Studying dispersal helps explain patterns of population connectivity, spread of diseases, and responses to environmental change.