1

Mon. Tues. Wed. Thurs. Fri.

Week ofNov. 10

Independent project analysis

Week ofNov. 17

River ecology lab – dress for weather

LabExam(bring calc.)

Week ofNov. 24

No lab – Thanksgiving

Nolecture

Week ofDec. 1

Independent project presentations

Exam 3

2

Species interactions

Introduction

Consumer/resources interactions(predation, herbivory, parasitism)

Competition

Mutualism

3

Interspecific Competition

Introduction

Competitive exclusion

How do species coexist?

4

-

-

Competitive interactions

A B

5

What are some resources that organisms compete for?

6

Intraspecific competition – competition betweenindividuals of the same species

Interspecific competition – competition betweenindividuals of different species

7

Two methods of competition

Interference competition

Exploitation competition

8

Figure 19.13

Exploitation

Interference

9

Interspecific exploitation competition

Intraspecific exploitation competition

Intraspecific interference competition

10

-

-

Competition may be asymmetric

A B

11

Figure 19.11

A

B

12

A B

Species A has a bigger effect on B than B has on A

How would you draw this?

13

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.

14

Competition

Introduction

Competitive exclusion

How do species coexist?

15

Figure 19.6

16

Figure 19.2

17

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

18

Competitive exclusion is difficult to witness outside of laboratory experiments

Why??

19

Figure 19.10

parasitoids – all use resourcesame way

20

Competition

Introduction

Competitive exclusion

How do species coexist?

21

How do species coexist?

1. Resource partitioning

2. Predation on one or more species

22

How do species coexist?

1. Resource partitioning-different species aren’t using the same

resource exactly the same way

23

.

.

..

.5 warbler speciesall eat insectsin spruce trees

24

How do species coexist?

2. Predation on one or more species

25

-

-

A B

26

-

-

A B

Consumer

-+

27

Mussel = dominant competitor

Bob Paineexperiments

28

+

+

Mutualistic interactions

A B

29

When species are in a mutualistic relationship what do they gain from each other?

30

Lichens

31

Obligate mutualism – species are so dependent

on each other that they cannot live without each

other

32

Acacia trees andacacia ants

33

Trees withoutants

Treeswithants

% o

f sh

oo

ts w

ith

her

biv

ore

s o

n t

hem

34

May25

June16

Aug.03

Aca

cia

hei

gh

t (c

m)

0

120

60

35

Which are more general? seed dispersal or pollination mutualisms

36

Figure 20.16

37

                 

  I

II

III

IV

Degree of lethality

low high

De

gre

e o

f re

sou

rce

sp

ecia

lizat

ion

low

h

igh

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.