I. I.Community Ecology A. A.Competition 3. 3.Resource partitioning Competitive exclusion can be...
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Transcript of I. I.Community Ecology A. A.Competition 3. 3.Resource partitioning Competitive exclusion can be...
![Page 1: I. I.Community Ecology A. A.Competition 3. 3.Resource partitioning Competitive exclusion can be minimized if competing species modify niches to reduce.](https://reader036.fdocuments.net/reader036/viewer/2022070404/56649f355503460f94c53032/html5/thumbnails/1.jpg)
I. Community Ecology
A. Competition3. Resource partitioning
• Competitive exclusion can be minimized if competing species modify niches to reduce overlap
• Usually involves dividing resource
![Page 2: I. I.Community Ecology A. A.Competition 3. 3.Resource partitioning Competitive exclusion can be minimized if competing species modify niches to reduce.](https://reader036.fdocuments.net/reader036/viewer/2022070404/56649f355503460f94c53032/html5/thumbnails/2.jpg)
Fig. 54.2
Anolis Dominican Republic
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I. Community Ecology
A. Competition4. Character displacement
• Resource partitioning may lead to directional selection on one or both species
• Directional selection may lead to divergence in traits
![Page 4: I. I.Community Ecology A. A.Competition 3. 3.Resource partitioning Competitive exclusion can be minimized if competing species modify niches to reduce.](https://reader036.fdocuments.net/reader036/viewer/2022070404/56649f355503460f94c53032/html5/thumbnails/4.jpg)
Fig. 54.4
![Page 5: I. I.Community Ecology A. A.Competition 3. 3.Resource partitioning Competitive exclusion can be minimized if competing species modify niches to reduce.](https://reader036.fdocuments.net/reader036/viewer/2022070404/56649f355503460f94c53032/html5/thumbnails/5.jpg)
I. Community Ecology
B. Predation• Involves consumption of prey by predator• Predator usually has adaptations to facilitate capture of
prey• Natural selection acts on both predator and prey
• Coevolution1. Strategies
a. Pursuit predation• Predators chase prey to capture them• Predator usually faster, stronger, &/or more agile than
prey• Some species hunt in groups
b. Ambush predation• Predators lie in wait for prey• Predators usually camouflaged or concealed• May involve lures
c. Aggressive mimicry• Ex: Bolas spider mimics odor of female moths to
attract male moths
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![Page 7: I. I.Community Ecology A. A.Competition 3. 3.Resource partitioning Competitive exclusion can be minimized if competing species modify niches to reduce.](https://reader036.fdocuments.net/reader036/viewer/2022070404/56649f355503460f94c53032/html5/thumbnails/7.jpg)
I. Community Ecology
B. Predation2. Predator avoidance
a. Escape• Running/Swimming/Flying away
b. Mechanical defenses• Ex: Porcupine quills, armadillo armor
c. Social behavior• Ex: Schooling, standing watch
d. Chemical defenses• Ex: Poison dart frog, skunk
e. Defensive coloration
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Cryptic coloration
- Canyon tree frog
Aposematic coloration
- Poison dart frog
Batesian mimicry Fig. 54.5
Müllerian mimicry
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Batesian Mimicry
Sam Crothers
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I. Community Ecology
C. Herbivory• Consumption of plants by animals• Most herbivores are small
• Ex: Insects, snails/slugs
• Herbivores adapted to consume plants• Some plants have anti-herbivore defenses
• Physical – Ex: Thorns, spines• Chemical – Ex: Nicotine in tobacco, pyrethrins in
chrysanthemums
• Coevolution has affected herbivore evolution• Ex: Monarch butterfly caterpillars can eat milkweed
• Toxic to most herbivores• Nearly exclusive access to food source• Can sequester noxious compounds for defense
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I. Community Ecology
D. Parasitism• Parasite benefits at expense of host
• Host harmed in process• Ex: Tapeworm absorbs nutrients from host digestive
system
• Endoparasites – Live within body of host• Ectoparasites – Live outside body of host• Parasitoids – Lay eggs on/in host; larvae feed
on host, eventually killing host• Many parasites have complex life cycles
Fig. 33.12
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Fig. 33.11Schistosoma mansoni
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I. Community Ecology
E. Disease• Widespread disease outbreaks may alter
community composition and dynamics• Ex: Dutch elm disease• Ex: Sudden oak death• Ex: Avian flu• Ex: West Nile virus
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I. Community Ecology
F. Mutualism• Symbiotic relationship in which both partners
benefit• Ex: Ants & acacia trees• Ex: Nitrogen fixing bacteria (Rhizobium) & legumes• Ex: Zooxanthellae & reef-building corals• Ex: Mycorrhizae & plants• Ex: Anemones & clownfish
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I. Community Ecology
G. Commensalism• One organism benefits, other isn’t harmed or
helped• Ex: Cattle egrets and cowbirds & ungulates (expose
insects while grazing)
• Hard to document (both species usually affected to some degree)
• Ex: Some commensal birds may remove ticks & other ectoparasites from herbivores