(b)A
population with large number of post-reproductive or older individuals and
lesser number of pre-reproductive individuals will show a negative growth rate
or decline growth.Age
pyramid Graphic
representation of different age groups found in a population with
pre-reproductive group at the base. Reproductive ones in the middle and
post-reproductive group at the top is called age pyramid.Age
pyramid have three kinds(i)
Triangular Age Pyramid The number of pre-reproductive is very large.
Number of reproductive individual is moderate and post-reproductive are
fewer. Population size is growing(ii)
Bell-shaped Age Pyramid The number of prereproductive and reproductive
individuals is almost equal. Post-reproductive individuals are comparatively
fewer. Population size is stable(iii)
Urn-shaped Age Pyramid Proportion of reproductive age group is higher
than the individuals in pre-reproductive age group. Number of
post-reproductive individuals is also sizable. It is declining population
with negative growth |