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. As one moves away from the origin, the probability decreases of finding individuals. One can calculate how far a given organism is expected to move during its lifetime based on s . Propagules Propagules are the seeds or larvae of sessile plants and animals. Wind, water currents, and animals often serve to aid dispersal of propagules.