Download The changes in population size

Environmental
Effects
Change in population
size due to various
environmental factors.
Objectives
• (12D) (Student Name READS)
Recognize that long-term survival of
species is dependent on changing
resource bases that are limited.
• (12F) (Student Name READS) Describe
how environmental change can
impact ecosystem stability
Population Growth
The changes in population size (population growth) can be
communicated in graphs.
Birth rate (number of organisms born) causes an increase in
population size.
Mortality (number or organisms that die) causes a decrease in
population size.
Besides birth and death rate, other factors will affect the
population growth of a given species in a particular habitat.
Resources
Food, water, shelter, and space are resources
that are limited, and organisms compete for
them as they struggle to survive.
BAMBOO is a
limited resource
due to human
interference
A limited resource base can affect the long-term
survival of a species, thus affecting the
population growth.
Limiting Factors
A resource that has the ability to LIMIT the population
growth is called a limiting factor.
1. Density-Dependent Limiting Factors: depend on the
size of the population. For example, an increase in
pandas would mean the bamboo has the chance of
running out.
Other examples: food, shelter, water, disease
transmission and ability to find a mate .
2. Density-Independent Limiting Factors: affect the
population regardless of its size. For example, if a
tsunami hits the panda habitat, the population will
decrease no matter what its size was at that moment.
Other examples: climate, weather and other
natural disasters
Carrying Capacity
Carrying capacity is the maximum amount of that
organism that the habitat can support with resources.
Once the panda population reaches a certain size, it
has reached its “maximum” and the resources may
begin to run out at that time.
Limiting Factors will
help the population
maintain a relatively
stable size!
Hunting, Fishing and
Predation
Hunting season for the deer population is highly regulated
and is determined when the population has a “boom”, or
sudden drastic increase due to birth-rate and reproduction.
Hunting can bring the population back to carrying capacity!
Fishing and predation
have the same affect
on population growth.
Population Growth
CONTROLLED
BY:
MAINTAINED
BY:
RESULTS
IN:
SUCH AS:
Population Growth
POPULATION
GROWTH
The maximum
number of organisms
(of one species) that the
environment can support.
CONTROLLED
BY:
CARRYING
CAPACITY
MAINTAINED
BY:
Factors that can limit
population growth by
causing it to slow down.
LIMITING
FACTORS
Hunting/Fishing
SUCH AS:
Water
availability
Lack of space
Lack of food
Predation
Disease
RESULTS
IN:
STABILIZATION
OF POPULATION
GROWTH
Sample Population Growth Curve
Sample Population Growth Curve
CARRYING
CAPACITY
LIMITING FACTORS COME
INTO PLAY AND LEVEL OFF
THE POPULATION SIZE
POPULATION IS
STABILIZING AT
CARRYING
CAPACITY.