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a. A population of poppies
grows in a meadow.
Populations of other flowers
grow among the red poppies.
b. Walruses congregate on a beach.the growth of human populations. Understanding hu-
man population change is important because the size of
the human population is central to most of Earth’s envi-
ronmental problems and their solutions.
Scientists who study population ecology try to deter-
mine the processes common to all populations
(Figure 7.1). Population ecologists study how
a population responds to its environment—
such as how individuals in a given population
compete for food or other resources, and
how predation, disease, and other environ-
mental pressures affect that population. En-
vironmental pressures such as these prevent
populations—whether of bacteria or maple
trees or giraffes—from increasing indefinitely.- Define population ecology.
- Explain the four factors that produce changes
in population size. - Define biotic potential and carrying capacity.
I
ndividuals of a given species are
part of a larger organization
called a population. Populations
exhibit characteristics that are dis-
tinct from those of the individuals in them.
Some of the features characteristic of popula-
tions but not of individuals are birth and death
rates, growth rates, and age structure. Study-
ing populations of nonhuman species provides
insight into some of the processes that affect
Population Ecology
LEARNING OBJECTIVES
What we learn about one population helps us make predictions about
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At first glance, the two populations shown here appear to have little in common, but they
share many characteristics.
population
ecology The branch
of biology that deals
with the number of
individuals of a
particular species
found in an area and
how and why those
numbers increase or
decrease over time.