Populations are groups of individuals that occur together at one place and time. A community is the populations of different species that live together. A population has various characteristics which are unique to the whole group and not to an individual in the group.
Some of the important properties of population are as follows:
1. Density: Population density is the size of any population in relation to some unit space. It is generally expressed as the number of individuals, per unit area or volume.
2. Growth rate: The population growth refers to the total number of increase in the individuals occupying an area. A rate is obtained by dividing the change by the period of time elapsed during the changes. Thus the growth rate of population is expressed as the number organisms added to the population per time. This is obtained by dividing the population increase by the time elapsed.
3. Natality: It refers to the average number of offspring produced by a population per unit of time.
4. Mortality: It is reverse to the natality and is defined as the number of individuals dying in a population per unit time.
5. Biotic: potential and environmental resistance: It is the inherent property of an organism to reproduce, tosurvive that is to increase in number.
6. Population growth form: The growth is a dynamic feature of an animal population. Population exhibit characteristic patterns of increase which are known as population growth forms. The two patterns are J shaped growth form and S shaped form.
7. Age and sex ratio: Age distribution influences both natality and mortality of a population.