Download How do species coexist?

Mon.
Tues.
Wed.
Thurs.
Fri.
Week of
Nov. 10
Independent project analysis
Week of
Nov. 17
River ecology lab – dress for weather
Week of
Nov. 24
No lab – Thanksgiving
Lab
Exam
(bring calc.)
No
lecture
Week of
Exam 3
Dec. 1
Independent project presentations
1
Species interactions
Introduction
Consumer/resources interactions
(predation, herbivory, parasitism)
Competition
Mutualism
2
Interspecific Competition
Introduction
Competitive exclusion
How do species coexist?
3
Competitive interactions
A
B
4
What are some resources that organisms compete for?
5
Intraspecific competition – competition between
individuals of the same species
Interspecific competition – competition between
individuals of different species
6
Two methods of competition
Interference competition
Exploitation competition
7
Figure 19.13
Exploitation
Interference
8
Intraspecific
interference
competition
Intraspecific
exploitation
competition
Interspecific
exploitation
competition
9
Competition may be asymmetric
-
A
B
10
Figure 19.11
A
B
11
Species A has a bigger effect
on B than B has on A
How would you draw this?
A
B
12
Which one of the following is not an example of
competition between species?
a. Blowflies and fleshflies breed in the same types
of carcasses, and both species experience reduced
reproduction rates when densities within carcasses
are high.
b. Sage plants produce a ring of bare ground
surrounding them.
c. Wolverines and mountain lions fight each other
for deer carcasses.
d. Spotted owls and great horned owls occupy the
same type of habitat.
13
Competition
Introduction
Competitive exclusion
How do species coexist?
14
Figure 19.6
15
Figure 19.2
16
Competitive exclusion principle: two species
that use the same limiting resource in the
same way cannot coexist
Limiting resource – a resource which is scarce
relative to the demand for it
17
Competitive exclusion is difficult to witness
outside of laboratory experiments
Why??
18
Figure 19.10
parasitoids – all use resource
same way
19
Competition
Introduction
Competitive exclusion
How do species coexist?
20
How do species coexist?
1. Resource partitioning
2. Predation on one or more species
21
How do species coexist?
1. Resource partitioning
-different species aren’t using the same
resource exactly the same way
22
5 warbler species
all eat insects
in spruce trees
.
.
.
.
.
23
How do species coexist?
2. Predation on one or more species
24
A
B
-
25
Consumer
+
-
A
B
-
26
Bob Paine
experiments
Mussel =
dominant
competitor
27
Mutualistic interactions
+
A
B
+
28
When species are in a mutualistic relationship
what do they gain from each other?
29
Lichens
30
Obligate mutualism – species are so dependent
on each other that they cannot live without each
other
31
Acacia trees and
acacia ants
32
Trees
without
ants
Trees
with
ants
33
% of shoots with
herbivores on them
Acacia height (cm)
120
60
0
May
25
June
16
Aug.
03
34
Which are more general? seed dispersal or
pollination mutualisms
35
Figure 20.16
36
high
low
Degree of resource specialization
I
II
low
III
IV
high
Degree of lethality
One way to classify these C/R
interactions is to characterize
how harmful the consumer is
to an individual resource
organism and how
specialized the consumer is
to a particular resource
species.
1) Label each of the quadrants
with one type of consumer
(herbivore, parasite,
parasitoid, and predator) and
give an example of each.
2) This graph is a generalization.
Sometimes a consumer that
is classified in one quadrant
may act more like a consumer
in another quadrant. Choose
one of these examples and
describe it.
37