ABSTRACT
Population is a group of individuals of one species that live together and interbreed. Populations change with time — for individuals are born and they die, and animals may come in from outside populations, or leave the home population to go elsewhere. Such changes allow populations to respond to changes in the environment, and ensure that the population is able to persist in the face of changes. From the point of view of wildlife management, we need to know the current sizes of populations, and the changes that are happening — to be able to rectify issues before they become too large. Wildlife conservation may demand that the populations of some species be increased (since they are extremely few in number), of some species be decreased (because they are exotic species harming the native flora and fauna), and of some species be kept constant (for they are doing just fine). To this end, several techniques have been developed to analyse and measure the populations.
Community is a group of populations of different species that live together and interact with each other. These interactions stabilise the communities, ensuring that they are able to resist changes, and come back to the normal state when the changes are reversed. However, communities are not static — they too change with time, through a process known as ecological succession, wherein communities evolve from simple pioneer communities such as lichens to complex climax communities such as forests. Throughout the process, the populations comprising the communities grow according to logistic equations, and interact according to Lotka-Volterra dynamics.
In this chapter, we analyse the topics of population growth and community organisation.
