1 Mon. Tues. Wed. Thurs. Fri. Week of Nov. 10 Independent project analysis Week of Nov. 17 River ecology lab – dress for weather Lab Exam (bring calc.) Week of Nov. 24 No lab – Thanksgiving No lecture Week of Dec. 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 AB

5 What are some resources that organisms compete for?

6 Intraspecific competition – competition between individuals of the same species Interspecific competition – competition between individuals of different species

7 Two methods of competition Interference competition Exploitation competition

8 Figure Exploitation Interference

9 Interspecific exploitation competition Intraspecific exploitation competition Intraspecific interference competition

Competition may be asymmetric AB

11 Figure A B

12 AB 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 parasitoids – all use resource same 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

warbler species all eat insects in spruce trees

24 How do species coexist? 2. Predation on one or more species

AB

AB Consumer - +

27 Mussel = dominant competitor Bob Paine experiments

Mutualistic interactions AB

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 and acacia ants

33 Trees without ants Trees with ants % of shoots with herbivores on them

34 May 25 June 16 Aug. 03 Acacia height (cm)

35 Which are more general? seed dispersal or pollination mutualisms

36 Figure 20.16

37 I II III IV Degree of lethality low high Degree of resource specialization low high 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.