1. Competition

2. Competition is an interaction between individuals, brought about by a shared requirement for a resource in a limited supply, and leading to a reduction in the survivorship, growth, and/or reproduction of the competing individuals

3. Competition

5. Two key points: 1.Resource being competed for must be limited in supply 2. Interaction is always negative

6. Competition Intraspecific competition - competition between members of the same species - thought to be especially strong because members of the same species have the same resource requirements – regulates population size Interspecific competition - competition between members of different species - can be very strong as well – also regulates population size, structures communities, influences natural selection

7. Mechanisms of Competition 1) exploitation competition (aka resource or scramble) - individuals exert negative influence on each other by using up resources that each need - competition is mediated indirectly through resource depletion - individuals don't need to come into contact to compete 2) interference competition (aka contest competition) - competitors directly interact with each other in the course of seeking a common resource

8. Coral reef community – Great Barrier Reef

11. Competitive Asymmetries Although competition has negative effects on the population as a whole, some individuals are more negatively effected than others

12. Flax

14. Orchard Grass

16. Territoriality Territoriality occurs when there is an active interference such that a more or less exclusive area, the territory, is defended against intruders by a recognizable pattern of behavior - individuals or groups are spaced out more than would be expected from a random occupation of suitable habitats

17. Golden-winged sunbird

19. Limpet – Patella cochlear

20. Patella grazing on crustose algae (A)

22. Corn

23. Law of Constant Final Yield

24. Georgii F. Gause

25. Paramecium

28. Competitive Exclusion Principle "Two competing species cannot coexist in a stable environment if both require the same limiting resource." - if two competing species do coexist in a stable environment, they do so because of niche differentiation - their realized niches are slightly different and thus competition between them is lessened

29. Robert MacArthur, 1930-1972

31. Caveats to Resource Utilization Curves 1) Are we examining right resource? Is something else really limiting? 2) Is there variation in when the resource is limiting? If it is only limiting occasionally, then it may not matter much. 3) How do we quantify resource use by species in nature? Do resource utilization curves have to be normal? Does competition change during life history changes in the species? 4) How does overlap really affect the species? Is overlap really only on 1 dimension?