Section 14-3 and 14-4
“Population”
Write everything
that is underlined
14.3 Population Density / 14.4 Population Growth
Section 14.3 KEY CONCEPT:
Each population has a density, a
dispersion, and a reproductive strategy.
14.3 Population Density / 14.4 Population Growth
I. Populations
1. Population density is a measurement
of the number of individuals living in
a defined space.
2. Population dispersion refers to how a
population is spread in an area.
• There are three types of dispersion
illustrated on the next slides:
14.3 Population Density / 14.4 Population Growth
a. clumped
14.3 Population Density / 14.4 Population Growth
b.uniform
14.3 Population Density / 14.4 Population Growth
c. random
14.3 Population Density / 14.4 Population Growth
• Survivorship curves:
– Type I: low level of infant mortality and an older
population
– common to large mammals and humans
– Type II: survivorship rate is equal at all stages of
life
– common to birds
and reptiles
– Type III: very high
birth rate, very high
infant mortality
– common to invertebrates
and plants
14.3 Population Density / 14.4 Population Growth
Section 14.4 KEY CONCEPT:
Populations grow in predictable
patterns.
14.3 Population Density / 14.4 Population Growth
I. Population Growth
1. The size of a population is always
changing.
2. Four factors affect the size of a
population:
a. Births
b. Deaths
c. Immigration
(Moving into an area)
d. Emigration
(Moving out of an area)
14.3 Population Density / 14.4 Population Growth
3.Exponential growth is a rapid
population increase due to an
abundance (lots of) of resources.
14.3 Population Density / 14.4 Population Growth
4. Logistic growth is due to a population
facing limited resources.
14.3 Population Density / 14.4 Population Growth
5.Carrying capacity is the
maximum number of
individuals in a population
that the environment can
support.
• This is due to limited resources
(food, shelter, space)
14.3 Population Density / 14.4 Population Growth
• A population crash is a dramatic
decline in the size of a population
over a short period of time.
14.3 Population Density / 14.4 Population Growth
6. A limiting factor is something that
keeps the size of a population down.
• Limiting factors can depend on the
density of individuals in the population
or not.
14.3 Population Density / 14.4 Population Growth
7. Density-dependent limiting factors are
affected by the number of individuals
in a given area.
– Predation
– Competition
– Parasitism
and disease
14.3 Population Density / 14.4 Population Growth
8.Density-independent limiting
factors limit a population’s growth
regardless of the density.
a.unusual
weather
b.natural
disasters
c.human
activities