Transcript Biotic Potential and Species Growth Capacity

Topic 2
Population
Dynamics
Students will be able to:
-describe the ways in which populations can change
-define carrying capacity and describe factors that affect it.
-describe the principles associated with survivorship curves including k- and r- strategists.
-describe and explain “S” and “J” population growth curves.
No population can grow indefinitely!
Species vary in their Biotic Potential
= the capacity for population growth
with unlimited resources and ideal
conditions.
Resources can include:
food oxygen water
Ideal conditions:
shelter
weather
light
space
no predation
nutrients
mates
Topic 2
Population
Dynamics
Students will be able to:
-describe the ways in which populations can change
-define carrying capacity and describe factors that affect it.
-describe the principles associated with survivorship curves including k- and r- strategists.
-describe and explain “S” and “J” population growth curves.
No population can grow indefinitely!
Number of sheep (millions)
Every environment has Environmental Resistance
= the combination of all factors that act to limit the growth of a
2.0
population (lack of
resources and or
1.5
environmental
conditions)
1.0
.5
1800
1825
1850
1875
Year
1900
1925
Topic 2
Population
Dynamics
Students will be able to:
-describe the ways in which populations can change
-define carrying capacity and describe factors that affect it.
-describe the principles associated with survivorship curves including k- and r- strategists.
-describe and explain “S” and “J” population growth curves.
No population can grow indefinitely!
The Biotic Potential + Environmental Resistance = Carrying Capacity
Number of sheep (millions)
Every environment has a CARRYING CAPACITY
= the maximum
2.0
number of individuals
1.5
of a given species
that can be sustained
1.0
indefinitely in a given
space.
.5
1800
1825
1850
1875
Year
1900
1925
Topic 2
Population
Dynamics
Students will be able to:
-describe the ways in which populations can change
-define carrying capacity and describe factors that affect it.
-describe the principles associated with survivorship curves including k- and r- strategists.
-describe and explain “S” and “J” population growth curves.
Factors that can change carrying capacity:
1. Competition within and between species.
2. Natural and human caused catastrophes.
3. Immigration and emigration.
4. Seasonal fluctuations in food, water,
shelter, and nesting sites.
Topic 2
Population
Dynamics
Students will be able to:
-describe the ways in which populations can change
-define carrying capacity and describe factors that affect it.
-describe the principles associated with survivorship curves including k- and r- strategists.
-describe and explain “S” and “J” population growth curves.
“J” population
growth curve
Population size (N)
A population that has few if any resource
limitations grows exponentially.
EXPONENTIAL GROWTH starts out slowly and
then proceeds faster
and faster as the
population increases.
Time (t)
Topic 2
Population
Dynamics
Students will be able to:
-describe the ways in which populations can change
-define carrying capacity and describe factors that affect it.
-describe the principles associated with survivorship curves including k- and r- strategists.
-describe and explain “S” and “J” population growth curves.
Topic 2
Population
Dynamics
Students will be able to:
-describe the ways in which populations can change
-define carrying capacity and describe factors that affect it.
-describe the principles associated with survivorship curves including k- and r- strategists.
-describe and explain “S” and “J” population growth curves.
“S or sigmoid”
population growth
curve
Population size (N)
LOGISTIC GROWTH involves initial exponential
growth and then there is a steady decrease in
growth as the population encounters
environmental resistance
and approaches carrying
K
capacity and levels off.
Time (t)
Topic 2
Population
Dynamics
Students will be able to:
-describe the ways in which populations can change
-define carrying capacity and describe factors that affect it.
-describe the principles associated with survivorship curves including k- and r- strategists.
-describe and explain “S” and “J” population growth curves.
r and K Selected Species
r-selected species = species with a high
biotic potential.
These species have many, small, offspring and give them little or
no care.
Examples are algae, bacteria, rodents, frogs, turtles, annual
plants, and most insects.
These species tend to be opportunists, reproducing rapidly
when conditions are favorable or when disturbances open up a
new habitat.
Topic 2
Population
Dynamics
Students will be able to:
-describe the ways in which populations can change
-define carrying capacity and describe factors that affect it.
-describe the principles associated with survivorship curves including k- and r- strategists.
-describe and explain “S” and “J” population growth curves.
r and k Selected Species
K-selected species = species with a low
biotic potential.
These species reproduce later in life, have small number of
offspring, and have long life spans.
Examples are mammals, birds of prey, and large and long-lived
plants.
These species tend to be competitors.