Mon Tues Wed Thurs Fri Week of Nov

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 II low Degree of resource specialization I 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, 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