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Mon. Tues. Wed. Thurs. Fri. Week of Nov. 10. Independent project analysis . Lab Exam (bring calc.). Week of Nov. 17. River ecology lab – dress for weather . Week of Nov. 24. No lecture . No lab – Thanksgiving . Week of Dec. 1. Exam 3.
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Mon. Tues. Wed. Thurs. Fri. Week of Nov. 10 Independent project analysis Lab Exam (bring calc.) Week of Nov. 17 River ecology lab – dress for weather Week of Nov. 24 No lecture No lab – Thanksgiving Week of Dec. 1 Exam 3 Independent project presentations
Species interactions Introduction Consumer/resources interactions (predation, herbivory, parasitism) Competition Mutualism
Interspecific Competition Introduction Competitive exclusion How do species coexist?
Competitive interactions - A B -
Intraspecific competition – competition between individuals of the same species Interspecific competition – competition between individuals of different species
Two methods of competition Interference competition Exploitation competition
Figure 19.13 Exploitation Interference
Intraspecific exploitation competition Intraspecific interference competition Interspecific exploitation competition
Competition may be asymmetric - A B -
Figure 19.11 A B
Species A has a bigger effect on B than B has on A How would you draw this? A B
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.
Competition Introduction Competitive exclusion How do species coexist?
Competitive exclusion principle: two species that use the same limiting resourcein the same way cannot coexist Limiting resource – a resource which is scarce relative to the demand for it
Competitive exclusion is difficult to witness outside of laboratory experiments Why??
Figure 19.10 parasitoids – all use resource same way
Competition Introduction Competitive exclusion How do species coexist?
How do species coexist? • Resource partitioning • Predation on one or more species
How do species coexist? • Resource partitioning • -different species aren’t using the same • resource exactly the same way
5 warbler species all eat insects in spruce trees . . . . .
How do species coexist? • 2. Predation on one or more species
- A B -
Consumer - - + A B -
Bob Paine experiments Mussel = dominant competitor
Mutualistic interactions + A B +
When species are in a mutualistic relationship what do they gain from each other?
Obligate mutualism – species are so dependent on each other that they cannot live without each other
Acacia trees and acacia ants
% of shoots with herbivores on them Trees with ants Trees without ants
120 60 Acacia height (cm) 0 May 25 Aug. 03 June 16
Which are more general? seed dispersal or pollination mutualisms
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. • 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. I III IV II low high Degree of lethality low high Degree of resource specialization