04 Population

A population refers to all the individuals of a species that live together in one place at one time. This definition allows scientists to refer to all different kinds of populations — bacteria,human, or animal, for example.

Populations tend to grow because pairs of individuals have many offspring over the period of their lifetime. Predicting how a population will grow is the job of demographers. These scientists study three main features of population in order to predict growth: size, density, and dispersion.

Population size is very important. The number of individuals in a population can affect the population's ability to survive. Smaller populations are more at risk of becoming extinct due to floods, fires, or other natural disaster

Population density is the number of people that live in a certain area such as a square kilometre. If the individuals in an area are few and far between, it is more difficult for them to get together and reproduce. Because of this, the reproduction rate is lowered.

The final important feature is dispersion, which is the way individuals are arranged in a particular space. The three main patterns of dispersion are: randomly spaced, evenly spaced, and clumped. If they are randomly spaced, there is no pattern. If they are regularly spaced, they are at regular intervals. And if they are clumped, they are located in clusters.

Word List

offspring : babies

intervals : amounts of space

clumped : a mix of many individuals in a small space and other spaces where there are not many individuals

You Practice

I. Answer the following questions.

1) What is a population?

2) What is the difference between population size and population density?

3) Why are smaller populations more at risk of becoming extinct?

4) What are the three main features of dispersion?

5) In the area where you live, is the population randomly spaced, evenly spaced, or clumped?

II. Word power—Use these words from the reading in sentences of your own.

1) offspring_____________________________________________

2) extinct_______________________________________________

3) density_______________________________________________

4) pattern_______________________________________________

5) cluster_______________________________________________

III. True / False / Not Given—Write T if the sentence is true, F if it is not true, or NG if there is no information about this sentence.

____ 1) Population can only refer to people.

____ 2) Demographers are scientists who predict population.

____ 3) If a population is clumped together, it is difficult for it to survive.

____ 4) If the reproduction rate is high, it is easier for a population to survive.

____ 5) Demographers can predict exactly how much a population will increase by in the next 20 years.