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CHAPTER 5 Evolution and Community Ecology Lesson 5.2 Species Interactions The zebra mussel has completely displaced 20 native mussel species in Lake St. Clair. Lesson 5.2 Species Interactions The Niche • Describes an organism’s use of resources and functional role in a community • Affected by an organism’s tolerance—its ability to survive and reproduce under changing environmental conditions • Often restricted by competition QuickTime™ and a decompressor are needed to see this picture. Lesson 5.2 Species Interactions Competition • Organisms compete when they seek the same limited resource. • In rare cases, one species can entirely exclude another from using resources. • To reduce competition, species often partition resources, which can lead to character displacement. QuickTime™ and a decompressor are needed to see this picture. Resource Partitioning Lesson 5.2 Species Interactions Predation (+/–) • The process by which a predator hunts, kills, and consumes prey • Causes cycles in predatory and prey population sizes • Defensive traits such as camouflage, mimicry, and warning coloration have evolved in response to predator-prey interactions. QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. • Some predator-prey relationships are examples of coevolution – the process by which two species evolve in response to changes in each other. QuickTime™ and a decompressor are needed to see this picture. Did You Know? A single rough-skinned newt contains enough poison to kill 100 people. Unfortunately for the newt, its predator, the common garter snake, has coevolved resistance to the toxin. QuickTime™ and a decompressor are needed to see this picture. Lesson 5.2 Species Interactions Parasitism and Herbivory (+/–) • Parasitism: One organism (the parasite) relies on another (the host) for nourishment or for some other benefit • Herbivory: An animal feeding on a plant Hookworm (a parasite) Did You Know? One study of Pacific estuaries suggests that parasites play an important role in keeping these ecosystems healthy by controlling host populations. QuickTime™ and a decompressor are needed to see this picture. Lesson 5.2 Species Interactions Mutualism (+/+) and Commensalism (+/0) Lichen: a symbiotic relationship between a fungus and a photosynthetic partner, such as an alga • Mutualism: a relationship in which two or more species benefit • Commensalism: a relationship in which one species benefits while the other is unaffected Did You Know? Symbiosis describes a long-lasting and physically close relationship between species in which at least one species benefits. M u t u a l i s m QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. QuickTime™ and a decompressor are needed to see this picture. C o m m e n s a li s m • http://www.youtube.com/watch?v=8YKA alZAqO4 Rhino song • http://www.youtube.com/watch?v=uxVM eLWzB_o