Transcript 14.4 Population and Growth Patterns TEKS 11B, 12A, 12D

14.4
Population and Growth Patterns
TEKS 11B, 12A, 12D
The student is expected to:
11B investigate and analyze how
organisms, populations, and communities
respond to external factors;
12A interpret relationships, including
predation, parasitism, commensalism,
mutualism, and competition among
organisms;
12D recognize that long-term survival of
species is dependent on changing resource
bases that are limited
14.4
Population and Growth Patterns
TEKS 11B, 12A, 12D
KEY CONCEPT
Populations grow in predictable patterns.
14.4
Population and Growth Patterns
TEKS 11B, 12A, 12D
Changes in a population’s size are determined by
immigration, births, emigration, and deaths.
• The size of a population
is always changing.
• Four factors affect the
size of a population.
– immigration
– births
– emigration
– deaths
14.4
Population and Growth Patterns
TEKS 11B, 12A, 12D
Population growth is based on available resources.
• Exponential growth is a rapid population increase due to an
abundance of resources.
14.4
Population and Growth Patterns
TEKS 11B, 12A, 12D
• Logistic growth is due to a population facing limited
resources.
14.4
Population and Growth Patterns
TEKS 11B, 12A, 12D
• Carrying capacity is the maximum number of individuals in
a population that the environment can support.
• A population crash is a dramatic decline in the size of a
population over a short period of time.
14.4
Population and Growth Patterns
TEKS 11B, 12A, 12D
Ecological factors limit population growth.
• A limiting factor is something that keeps the size of a
population down.
• Density-dependent limiting factors are affected by the
number of individuals in a given area.
14.4
Population and Growth Patterns
TEKS 11B, 12A, 12D
• Density-dependent limiting factors are affected by the
number of individuals in a given area.
– predation
– competition
– parasitism
and disease
14.4
Population and Growth Patterns
TEKS 11B, 12A, 12D
• Density-independent limiting factors limit a population’s
growth regardless of the density.
– unusual weather
– natural disasters
– human activities