Chapter 4, Problem 24A

Summary Introduction

To determine:

The term that describe the scenario in which “twenty percent of a population is in pre-reproductive years, fifty percent are in reproductive years and thirty percent is in the post reproductive years”.

Introduction:

A population can be defined as a group of individuals of the same species living in the same geographic area. A population has certain attributes that an individual organism does not have such as birth rate, death rate, age structure and sex ratio.

Answer to Problem 24A

The given scenario can be described by the term age structure.

Explanation of Solution

The density of population fluctuates due to following reasons:

Natality (B): it refers to the number of births in a given period that are added to initial density.

Mortality (D): it refers to the number of deaths that are deleted from the initial density.

Immigration (I): it refers to the number of individuals who have come into the habitat from somewhere else and added to the population.

Emigration (E): it refers to the number of individuals who left the population and migrated somewhere else

So, if N is the population density at time t, then population density at time t+1 can be shown as:

N_t+1 = N_t + ( B+I ) − ( D+E )

In case, where the birth rate is equal to death rate, the growth rate of the population will be zero as no new individual is adding to a population and this case refers to zero population growth.

Age structure is the number of males and females in different age groups named pre-reproductive, reproductive and post-reproductive ages.