Study Guide - Chapter 8
Study Guide – Chapter 8
is the study of how populations change through time, particularly
(total numbers of individuals) and
individuals per unit area) and
If we understand dynamics of living
organisms, we understand the environmental variables that affect populations and
communities, which allows us to try and conduct our activities with as little impact on
natural systems as possible.
Obviously we have a long way to go.
Most populations in nature have a clumped distribution, in ecological lingo we call them
This makes sense, as water, soil types, vegetation, etc. often occur
in disjunct (patchy) distributions, and the living organisms respond to these
As the book also mentions, living in a group can increase
your chances of survival (prey packs), increase your chances of finding food
(predator packs), and increase the likelihood of reproducing, the most critical part of
the natural selection game.
Populations change size through the combined effects of
, and emigration
If these factors are balanced, a population will stay
about the same size, if one or more of them change substantially, populations will
increase or decline.
We have already looked at the human population, immigration
and emigration continue to move people around, but our population growth on a
world scale is primarily due to stable birth rates and falling death rates – the world
population is in a demographic transition.
Most species live longer than one year,
and hence also have an
; again, we have looked at the age structure
of the human population, and the consequences of different types of age structures
(remember expansive and constrictive? Pre-reproductive, reproductive, and post-