This type of dispersion results from interactions with other individuals and is designed to minimize contact by providing a minimum distance between individuals. This type of distribution can be due to a tendency to form social groups or to clumping of resources. The observed distributions are often compared with the random distribution model as represented by the Poisson distribution . Population Density Estimation One of the most frequent activities undertaken by ecologists is estimating the density of individuals within populations. Density is usually defined as the number of individuals per unit area .
Density is more directly related to ecological conditions.
Therefore, it is more important than total population size. Generally, organisms are denser where the resources are readily available. Methods for estimating density Samples of the total population are counted within plots of known size, which is easy to do for sessile organisms. Natal dispersal is the movement of young organisms. Genetic analyses of populations are frequently done to estimate dispersal distances of individuals from populations.