Download Types of symbiosis - Coleman High School

Symbiosis
Mutualism | Commensalism | Parasitism
Learning Objectives
• Compare and contrast the three types of symbiosis
• Evaluate relationships to determine the type of symbiosis
occurring
Mutualism
• Symbiosis – a close
ecological relationship
between two species
• Types of symbiosis
– Mutualism
– Commensalism
– Parasitism
• Mutualism – an ecological
relationship in which both
species benefit
– Ex) Bees gain food,
flowering plants gain gamete
diversity
Commensalism
• Commensalism – an ecological relationship in which one
species benefits and the other is not affected
– Ex) Barnacles gain nutrients, whales are not affected
Parasitism
• Parasitism – an ecological
relationship in which one
species benefits and the
other is harmed
• Host – the organism that is
harmed by the parasite
• Parasite – the organism that
benefits from the host
• Ex) Tick gains
nutrients, dog loses
blood and may be
exposed to disease
Types of Symbiosis
Type of
Symbiosis
Mutualism
Commensalism
Parasitism
Species
One
Species
Two
Determining Types of Symbiosis
• To determine the type of symbiosis
Step 1 Write the names of the two species.
Step 2 Determine how the first species is affected.
Step 3 Determine how the second species is affected.
Step 4 Determine the type of symbiosis occurring.
Determining Types of Symbiosis Example
Ex) A fungus is found on the bottom of some people’s feet. The
fungus absorbs nutrients from the human it grows upon. The
fungus is not fatal. What ecological relationship does this
represent?
Step 1
Write the names of the two species.
Step 2
Determine how the first species is affected.
Human Fungus
Human Fungus
Step 3
Determine how the second species is affected.
Human Fungus
Step 4
Determine the type of symbiosis occurring.
Parasitism
Does the result make sense?
Yes.
Graphing Symbiosis
• Ecologists determine the type of symbiosis occurring by
graphing the populations of the two species over time
Community Dynamics
Predator-Prey Relationships |
Limiting Factors & Carrying Capacity
Learning Objectives
• Describe predator-prey relationships
• Recognize how limiting factors affect populations
• Explain rates of growth in a population
Predator-Prey Relationships
• Predation – relationship in which one organism hunts
and kills another for nutrition
• Predator – an organism which hunts and kills another
organism (ex: bear and snake)
• Prey – the organism which is killed
by the predator (ex: fish and frog)
Predator-Prey Relationships
• Prey populations determine predator populations
– As hare (prey) population increases, lynx (predator) population
increases
– As hare (prey) population decreases, lynx (predator) population
decreases
Predator-Prey Relationships
Late 1960s
1. An increase in moose
population causes increase
in wolf population.
2. Increased wolf population
causes decrease in moose
population.
1980
1. Wolf population is
decimated by disease.
2. Decreased wolf population
allows moose population to
increase.
Limiting Factors and Carrying Capacity
• Biotic potential – the highest rate of reproduction
possible for a population under ideal conditions
• Exponential growth – extremely high rate of growth
experienced by a species that reaches its biotic potential
• Limiting factors keep growth rates in check
– Limiting factors – external factors or environmental conditions
that affect population size
Limiting Factors and Carrying Capacity
• Density-dependent factors – natural resources that
affect population growth as a result of density
– Ex) Food, water, and space, predation, disease, and availability of
mates
• Density-independent factors – environmental
conditions that affect a population regardless of its density
Limiting Factors and Carrying Capacity
• Density-independent factor: weather
– Grey squirrels must find shelter during the winter
– Does not depend on the density of the population
Limiting Factors and Carrying Capacity
• Density-independent factor: human activities
– A new dam affects all densities of populations
Limiting Factors and Carrying Capacity
• Population Growth
– Growing populations have a positive growth rate
– Decreasing populations have a negative growth rate
– Populations that are neither growing nor decreasing are in a state
of equilibrium
• Carrying capacity – the point at which a population reaches a state of
equilibrium and there is no net gain or loss of individuals
Limiting Factors and Carrying Capacity
1. Initially, populations
have exponential
growth.
2. Limiting factors slow
population growth.
3. Population reaches its
carrying capacity.
Community Dynamics
External Dynamics | Competition
Learning Objectives
• Analyze how organisms, populations, and communities
respond to external factors
• Compare interspecific and intraspecific competition
External Dynamics
• Populations constantly change
• Factors that affect population size
– Births – increase population size
– Deaths – decrease population size
– Immigration – increase population size
• Immigrate – the movement of organisms into an area
– Emigration – decrease population size
• Emigrate – the movement of organisms out of an area
External Dynamics
• External factors and
environmental
conditions
– Directly affect organisms,
populations, and
communities
– Affect the availability of
resources
• Organisms must adapt in
order to survive
External Dynamics
• Natural disasters
– Forest fires, hurricanes,
floods, droughts, and
earthquakes
– Affect organisms and
resources
• Community impact
– Populations are
interrelated and affect
one another
Competition
• Competition – occurs when two organisms require the
same resource to meet their needs
• Organisms must compete for resources to survive
Competition Dynamics
1.
2.
3.
4.
Food is scarce for deer in
winter.
Competition increases in
deer population.
Deer population decreases.
Wolves feed on deer.
– Competition increases over
scarce deer.
5.
Competition contributes to
limited population growth
for both the deer and wolf
populations.
Competition
• Intraspecific
competition – organisms
of the same
species compete for
resources within the
ecosystem
– Ex) Diatoms grown in lab
compete for space and light
– Leads to population
decrease
Competition
• Interspecific competition – occurs between
different species for resources within an ecosystem
– Keeps the growth rate of populations in check