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Chapter 54 Community Ecology

Chapter 54 Community Ecology. Essential Knowledge. 2.d.1 – All biological systems from cells and organisms to populations, communities, and ecosystems are affected by complex biotic and abiotic interactions involving exchange of matter and free energy (54.1 - 54.5).

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Chapter 54 Community Ecology

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  1. Chapter 54 Community Ecology

  2. Essential Knowledge • 2.d.1 – All biological systems from cells and organisms to populations, communities, and ecosystems are affected by complex biotic and abiotic interactions involving exchange of matter and free energy (54.1 - 54.5). • 2.e.3 – Timing and coordination of behavior are regulated by various mechanisms and are important in natural selection (54.1). • 4.a.5 – Communities are composed of populations of organisms that interact in complex ways (54.1 & 54.2).

  3. Essential Knowledge • 4.a.6 – Interactions among living systems and with their environment result in the movement of matter and energy (54.2). • 4.b.3 – Interactions between and within populations influence patterns of species distribution and abundance (54.1). • 4.c.4 – The diversity of species within an ecosystem may influence the stability of the ecosystem (54.2).

  4. Community Ecology • The study of the interactions between the species in an area

  5. Interspecific Interactions • Interaction between species • May be positive, negative, or neutral • Ex: 1. Coevolution 2. Predation 3. Mimicry 4. Competition 5. Symbiosis

  6. Coevolution • When two species have reciprocal evolution to each other • Ex: • Flowers and their pollinators

  7. Predation (+/-) • Predator and prey relationships • Ex – Lynx and Hares

  8. Predation • Often results in interesting defenses or adaptations • Ex: • Plant defenses • Cryptic coloration • Aposematic coloration

  9. Cryptic Coloration • A passive defense where the prey is camouflaged against its environment

  10. Aposematic Coloration • The use of conspicuous colors in toxic or unpalatable organisms to warn off predators Poison Arrow frogs

  11. Mimicry • Defense mechanism where the mimic has a resemblance to another species, the model • Types: • Batesian • Mullerian

  12. Batesian Mimicry • Palatable species mimics an unpalatable model Hawk moth larva Snake

  13. Mullerian Mimicry • Two unpalatable species resemble each other Yellow Jacket Cuckoo Bee

  14. Competition • When two species rely on the same limiting resource • Intraspecific competition usually more severe than Interspecific competition • Why?

  15. Competitive Exclusion Principle • Predicts that two species with the same requirement can not co-exist in the same community • One species will survive and the second will go extinct

  16. Ecological Niche • The n-hyperspace of requirements for a species • How a species “fits into” an ecosystem • Species can not have niche overlap; the Competitive Exclusion Principle

  17. Niche Types 1. Fundamental - what a species is theoretically capable of using 2. Realized - what a species can actually use

  18. Resource Partitioning • A way that species avoid niche overlap by splitting up the available resources • Ex: Anolis lizards

  19. A. distichus A. insolitus

  20. Symbiosis • When two different species live together in direct contact • Types: 1. Parasitism 2. Commensalism 3. Mutualism

  21. Parasitism (+/-) • Parasite harms the host • Parasites may be external or internal • Well adapted parasites don't kill the host

  22. Parasitic behavior: A female Nasonia vitripennis laying a clutch of eggs into the pupa of a blowfly (Phormia regina)

  23. Commensalism (+/o) • One partner benefits while the other is unchanged • Ex. – Cattle and Egrets

  24. Mutualism (+/+) • Both partners benefit from the interaction • Ex: Pollinators and flowers Acacia Tree and Ants

  25. Prairie dogs are a keystone species in the Great Plains region of the U.S. and Canada. Keystone species p. 1204 • A keystone species is a plant or animal that plays a unique and crucial role in the way an ecosystem functions. Without keystone species, the ecosystem would be dramatically different or cease to exist altogether. • Prairie dogs are a keystone species in the Great Plains region of the U.S. and Canada

  26. Keystone species • A keystone as an arch's crown secures the other stones in place. Keystone species play the same role in many ecological communities by maintaining the structure and integrity of the community.

  27. Keystone species • often, but not always, a predator. • A keystone species' disappearance would start a domino effect. Other species in the habitat would also disappear and become extinct. In terrestrial environments, fire ants function as keystone predators by suppressing the numbers of individuals and species of arthropods that could be harmful to agriculture.

  28. Succession Changes in species composition over time

  29. Succession Stages • Sere: unstable stage usually replaced by another community • rock lichen moss grass shrub tree forest • Climax: stable stage, self-reproducing

  30. Succession Types 1. Primary 2. Secondary

  31. Primary Succession • Building a community from a lifeless area • Ex: volcanic islands glaciated areas road cuts

  32. Glacier Bay, Alaska • Example of primary succession (p. 1209)Glacial retreat

  33. Comment • The first example of primary succession was worked out on the Indiana Dunes • Stages: • Open Beach • Beach Grasses • Conifers (Junipers and Pines) • Oaks • Beech-Maple forest (Climax)

  34. Secondary Succession • Where a community has been disturbed and the soil is mostly intact • Ex: • Cutting down a forest • Blow-outs on the Dunes

  35. Causes of Succession 1. Autogenic Factors 2. Allogenic Factors

  36. Autogenic Factors • Changes introduced by the organisms themselves • Ex: toxins acids

  37. Allogenic Factors • Outside disturbances • Ex: FireFloods

  38. Point • If you understand the causes and controlling factors of succession, you can manipulate them

  39. Biogeography • Study of the past and present distributions of individual species and communities

  40. Latitudinal Gradients

  41. Range Limitations 1. Lack of dispersion 2. Failure to survive in new areas 3. Retraction from former range area

  42. Proof • Fossil Evidence • Pollen Studies • Transplant Experiments

  43. Islands • Special cases in Biogeography • Must be colonized from other areas

  44. Island Species Factors • Island size • Distance from mainland

  45. Island Size • Small islands hold few species • Why? • Fewer niches available for species to occupy

  46. Distance from Mainland • Closer islands have more species • Why? • Easier for colonization

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