Question

Which age-structure pattern reflects a population with a declining population?

A) the pre-reproductive, reproductive and post-reproductive age classes are of equal sizes
B) the pre-reproductive age classes are larger than the reproductive or post-reproductive age classes
C) the reproductive age classes are smaller than pre- and post-reproductive age classes
D) the youngest, or pre-reproductive, age classes are the smallest

Answer 1

The age-structure pattern for a declining population is one where the youngest age classes are the smallest, which suggests an inverted pyramid configuration in age-structure diagrams.

Step-by-step explanation:

The age-structure pattern that reflects a population with a declining population is when the youngest, or pre-reproductive, age classes are the smallest. This situation is described by option D. A declining population typically has a higher proportion of older individuals and fewer young or pre-reproductive individuals. In age-structure diagrams, this is represented by a top-heavy configuration, which can resemble an inverted pyramid, corresponding to stage 4 of population growth models. Developed countries with low birth rates and an aging population, like Italy, often exhibit this age structure, leading to a slow or negative population growth.