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Published byLynn Watts Modified over 8 years ago
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COMMUNITIES
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Key Properties of Communities Diversity –Species richness: total # of species –Species diversity: high if no one species predominates Prevalent form of vegetation (terrestrial communities) Stability-ability to resist change after disturbance Trophic structure-feeding relationships
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COMMUNITY INTERACTIONS Helpful? Harmful? Or no effect?
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Interspecific Interactions in Communities Interspecific interaction #1 Competition
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Competitive exclusion When cultured separately, both species go to carrying capacity When cultured together, COMPETITION! Slight reproductive advantage leads to elimination of inferior species
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Restating Competitive Exclusion in Nature Niche: how a species fits into an ecosystem Restate competitive exclusion principle: similar species CANNOT coexist if they have the exact same niche
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Competitive Exclusion
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Resource Partitioning Competition between these lizards in Dominican Republic is minimized because lizards’ perches vary
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Black skimmer seizes small fish at water surface Flamingo feeds on minute organisms in mud Scaup and other diving ducks feed on mollusks, crustaceans, and aquatic vegetation Louisiana heron wades into water to seize small fish Brown pelican dives for fish, which it locates from the air Avocet sweeps bill through mud and surface water in search of small crustaceans, insects, and seeds Oystercatcher feeds on clams, mussels, and other shellfish into which it pries its narrow beak Dowitcher probes deeply into mud in search of snails, marine worms, and small crustaceans Herring gull is a tireless scarialavenger Ruddy turnstone searches under shells and pebbles for small invertebrates Knot (a sandpiper) picks up worms and small crustaceans left by receding tide Piping plover feeds on insects and tiny crustaceans on sandy beaches Resource Partitioning in Coastal Community
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Resource partitioning with warbler species
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Three-way community interaction 1) caterpillar injures plant 2) caterpillar saliva stimulates plant to release a wasp- attracting vapor 3) wasp stings caterpillar and then lays eggs in caterpillar
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Interspecific Interactions in Communities Interspecific interaction #2 Predation
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Predator-Prey Relations How do plants avoid being eaten by herbivores? Physical Defense: ThornsChemical Defense: Poison
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Adaptations Related to Predation Organisms have evolved certain adaptations –Predator adaptations (claws, poison, jaws…) –Plant defenses (thorns, spines, chemicals…) –Prey defenses (peppered moth)
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Cryptic Coloration= Camouflage Evolution of camouflage- example (video clip)example (video clip)
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Bright Coloration-warning symbol
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Mimicry is another form of coloration defense. Mimicry – a phenomenon in which one species benefits by a superficial resemblance to an unrelated species
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Deceptive Coloration
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Two forms of Mimicry: 1)Batesian mimicry – a palatable or harmless species mimics an unpalatable or harmful species. What would be the advantage of this? 2)Müllerian mimicry – two or more unpalatable or brightly colored species resemble each other What would be the advantage of this?
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Batesian Mimicry
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Can you tell the difference?
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Unpalatable Palatable
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Blue Jay eats Monarch
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Vomits Monarch
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Learns to avoid Monarchs!
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Cuckoo bee Yellow jacket Both have stingers that release toxins Müllerian mimicry
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What is a KEYSTONE? Keystone Species Keystone Predators
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Keystone Species http://www.grinningplanet.com/2004/06-22/keystone-species- article.htm http://www.grinningplanet.com/2004/06-22/keystone-species- article.htm
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Keystone Predators \
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Watch video clips… Camouflage, Combat, and Sharkboy (plus a good blood review!)Camouflage, Combat, and Sharkboy Trials of life Video
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Interspecific interaction #3: Symbiotic Relationships
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Symbiotic Relationships An interspecific interaction in which one species, the symbiont, lives in or on another species, the host
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Parasitism = (+/-) interactions A symbiotic relationship in which one organism benefits while the other is harmed The parasite –Obtains its nutrients by living in or on its host organism
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Commensalism = (+/0) interactions Symbiotic relationship where one species benefits and the other is not affected positively or negatively Possible examples – 1.Clown fish and anemone 2.Remora (sucker fish) and sharks
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Mutualism = (+/+) interactions Interactions where both species benefit Examples: flowers and pollinators Protozoa and termites Nitrogen fixing bacteria in roots of plants
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Yucca and Yucca Moth
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Summary Find examples of these from the video Living Together, in the Trials of Life series.
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Species richness vs. diversity Community 1 vs. Community 2: how do they compare in richness and how do they compare in diversity
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Prevalent Vegetation Looks not only at type of vegetation, but also how arranged….this determines the type of animals that live in a community
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Community Stability How does a community respond after a disturbance? Ex: cedar and hemlock trees withstands lightning fires Versus Grassland devastated by a fire
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Trophic Structure
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