chapter 28
TRANSCRIPT
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Chapter 28
Community Interactions
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Why Are Interactions in Communities Important?
• Community • Interactions limit population size
– Balance between resources and # of individuals
– Exotic species may upset balance
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• Interactions influence evolutionary change– Coevolution
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Interspecific Competition
• Each species has a unique place in its ecosystem– Ecological niche
• Niches of species never overlap completely– Competitive exclusion
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• Competitive exclusion may help determine population distribution– Fundamental niche vs. Realized niche
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• Species may evolve to reduce competition– Resource partitioning
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What are the Effects of Predator-Prey Interactions
• Coevolution
• Predators consume prey
• Parasites feeding off host but may not kill the host– Herbivores
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• Camouflage– Hiding in plain site
Blending in
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resemble specific objects
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Camouflage assists predators
Camouflage can be beneficial to predators as well
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• Bright colors or chemical defenses may warn off predators
Warning coloration
Startle coloration
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Warning mimicry
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Visual and behavioral mimicry
Chemical Warfare
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• Plants have defenses against herbivores – Chemicals
– Tough outer parts
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• Symbiosis
– Communalistic • + / neutral
– Mutualistic• + / +
– Parasitic• + / -
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Mutualism
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Keystone species
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How do Communities Change Over Time
• Succession– Pioneers– Climax community
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Primary Succession
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Secondary Succession