#### Population ecology

The population ecology is the branch of the ecology that deals with the variation in the population size and structure and also the population dynamics. The characteristics of the population include the population density, dispersion , age structure, natality,mortality, biotic potential and growth rate. The size of the population in relation to the space occupied by them is known as the population density. The dispersal can be defined as the means by which new or the depopulated areas are colonized and the equilibrium is established.It is classified as regular, random and clumped dispersion. The age structure classified the life as the pre- reproductive ,reproductive and the post-reproductive periods. Natality is the inherent and the natural ability of the population to increase its proportion. Absolute natality rate= ΔNn / Δt The specific natality rate = ΔNn / (nΔ t) where, N = Initial number of the organisms n = new individuals of the organisms t = time The death of an organism due to the accidental case or by the age is known as the mortality rate. It is also considered as the survival rate that is greater than the death rate. If the latter is expressed as a fraction. M then the survival rate is I-M.

#### Biotic potential, population growth curves

Biotic potential is the highest possible vital index of the species with the high fertility rate. The population dynamics in the branch of the life science that studies about the short-term and the long-term changes in the size and the age composition of the population and the biological and the environmental processes influencing those changes. The growth is one of the dynamic features of the population size increase. There are two types of the curve a. S- Shaped curve or the logistic curve or the sigmoid curve. b. J- shaped curve or the geometric curve The S- shaped growth curve can be represented by: dN/dt = r. N (K-N)/ K The growth is given by the equation (in the J- shaped curve) dN/ dt = r. N