Survivor:
Who Will Be the Best Competitor?
How environmental change affects
competition
Competition
• Organisms require
resources from their
environment to grow,
survive and reproduce
• Plants in the rainforest
require sunlight, water and
nutrients
• Different species of plants
compete for these
resources
Competition Examples
Within Species Competition Video
Clover sprouts compete above and below ground.
http://www.youtube.com/watch?v=d26AhcKeEbE&feature=related
Between Species Competition Video
Damselfish defend territories to compete with other fish.
http://www.youtube.com/watch?v=9YR7VfsR5iA&feature=related
Competition Examples
Competition Examples
What examples of competition can you think of?
Why is it important to understand
competition?
• Predict if species can coexist
• Predict what will happen if
– species are lost (extinction)
– species are introduced
• Invasive species
• Biological controls
Environmental Change =
Competition Change
If global warming decreased rainfall,
• how would that affect plant competition?
Sea lamprey are an invasive species that attack fish
and suck their blood.
If sea lamprey, invade Lake Michigan
• how would that affect fish
competition?
Species Loss in Stickleback Fish
• Historically 2 species that
differ in
– Color, size, shape, behavior
– Feeding & mating habitats
• One species mates in
the open; the other
species mates in the
vegetation
Invasive Species Changed Mating Habitats
• Recent crayfish introduction
• Ecological changes:
- Vegetation loss
- Increased turbidity
- Water color
Historical Conditions
Current Conditions
Loss of habitat increased species competition
• Bigger males compete better
• Bigger males = more aggression = gain a territory
• Need a territory to build a nest and attract females
Loss of habitat increased species competition
0.03
0.02
0.01
Aggression
After habitat
loss
0
Before habitat
loss
-0.01
-0.02
0
1
largest
2
3
4
smallest
Male Size Rank
5
Loss of habitat increased species competition
0.03
0.02
Benthic
Species
0.01
Aggression
Limnetic
Species
After habitat
loss
0
Before habitat
loss
-0.01
-0.02
0
1
largest
2
3
4
smallest
Male Size Rank
5
Loss of habitat increased species competition
0.03
0.02
0.01
Aggression
After habitat
loss
0
Before habitat
loss
-0.01
-0.02
0
1
largest
2
3
4
smallest
Male Size Rank
5
Loss of habitat increased species competition
0.03
0.02
0.01
Aggression
After habitat
loss
0
Before habitat
loss
-0.01
-0.02
0
1
largest
2
3
4
smallest
Male Size Rank
5
Competition: The Game
Species A vs. Species B
•
•
•
•
•
•
Environment 1
Species A = Red-filtered vision
Species B = Blue-filtered vision species
Multiple types of available food items
60 seconds to collect as many food items as you can
You need 5 units of food to survive until tomorrow
You must
– Pick up one food item at a time and return it to your stomach (cup)
– Walk carefully
– Not physically interfere with other organisms
Competition: The Game
• Use your worksheet to record food items
eaten by each member of your species
Competition: The Game
Species A vs. Species B
Environment 2
A disease has drastically reduced the number of one of the
prey items.
You must forage for food in this new environment.
Competition: The Game
• Use your worksheet to record food items
eaten by each member of your species in
Environment 2.
• Graph total # of food items of each color
eaten by all members of your species.
• How do results compare between
environments? (Groups prepare to report out)
Competition: The Game
• How do results for each species compare?
Competition: The Game
• What other changes to the game environment
can you imagine?
• Small groups develop ideas
• Entire group votes on one question to test
• Make predictions
• Test question and interpret results
Competition is Costly
• Competing takes energy and time
• Poor competitors get less of the resources
(food, territory)
• This leads to lower survival and reproduction
How can organisms reduce this cost?
Reduce competition by specializing
Eats detritus (dead material
on pond bottom)
Eats shrimp that swim in pond
Reduce competition by specializing
= Niche differentiation
Eats invertebrates in the
sediment of the lake bottom
Eats plankton that swim in
open water of the lake
Competition in Bioenergy Plots
How might competition be important in
bioenergy plots?