Dispersion Within Populations
The most common dispersion pattern is clumped. A clumped pattern is indicated by small groups of a particular species living together. For example, wolves within a population live in packs, and while they may move from one den to another, the pack remains intact. All social or community animals (such as herds of zebra or wildebeest) live in clumped dispersion patterns. Other examples of populations exhibiting a clumped dispersion pattern include mushrooms, meerkats, ants, bees, and gorillas, where individuals live in clumps according to the availability of resources, such as suitable soil conditions.
Uniform dispersion occurs when individuals of a species live in equally spaced sections of an ecosystem. The pattern often forms when resources such as sunlight or food are limited. Typical organisms that are found in uniform dispersion patterns include some nesting birds (gannets and penguins), smaller cacti or shrubs (barrel cactus or mesquite), and redwoods. Penguins typically have uniform dispersion because the distance between individual penguin nests is maintained by aggressive interactions. Gannets have limited space for nesting and limited materials for building nests; thus, they share space relatively evenly. Cacti compete for water, while redwoods compete for sunlight.Random dispersion patterns tend toward unpredictability; each individual's position is independent of other individuals in the population. A dandelion produces seeds that are spread by the wind, so the location of new dandelions is heavily influenced by wind direction. Many spiders use aerial dispersion to seek new homes, casting a balloon-like structure that catches the wind. Some seeds may be dispersed by water movement, such as flowing rivers or flash floods. Seeds may also stick to an animal's fur and be dropped in new locations, where they germinate and produce new individuals. Seeds in fruit, such as berries, are dispersed through animal waste. The fruit is eaten, but the seeds pass through the animal's digestive tract and are eliminated as fecal matter. Lupines, geraniums, and violas disperse their seeds by explosion, literally flinging the seeds away from the parent plant.