Question

State and define the attributes of a population.

Answer 1

Hint: They are the characteristics of the population, and are a function applied to the entire population, and determined through the variate values on individual units.

Complete answer:
A population is all the organisms of the same group or species living in a particular geographical area and are capable of interbreeding. The population that occupies a minimal area is smaller in size, such a population is called the local population. A group of such a closely related local population is called meta-population.

Attributes of population:
> Population density – it refers to the size of any population concerning some unit of space it is expressed in terms of the number of individuals or biomass per unit area or volume. Populations are always in a dynamic state. As they change over time and space, no population has a single structure.
> Birth rate (Natality) – it is the rate of production of new individuals per unit of population per unit time. It is an expression of the production of new individuals in the population by birth, hatching, germination, or fission.
> Death rate (Mortality) – it is the rate of loss of individuals per unit time due to death or different environmental changes, competition, predation, etc.
> Population growth – the size of the population for any species, keeps changing with time, it's not static. It increases characteristically. When the number of individuals of the population is plotted on the y-axis and times on the x-axis, a curve is formed called population growth.
> Sex ratio – an individual is either a male or a female.
- Example: The sex ratio of a population is 60% females and 40% males.
> Age distribution – it influences natality and mortality. It is directly related to the growth rate of the population and may be constant or variable.
> Age pyramids – it is a model in which the number or proportions of individuals in various age groups at any given time are presented.

Note: Population growth is of two types:
- Sigmoid curve – The population increase is very slow in the beginning, a very rapid increase in the middle phase, and in the last phase population increase slowed down to attain an equilibrium.
- J-shaped curve – No increase in population size in the first phase, after some time it starts multiplying rapidly. This continues till food materials are present but due to an increase in population size food gets limited leading to population decrease.