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Chapter 52

Chapter 52. Community Ecology. Ecological niche Distinctive lifestyle and role of an organism in a community Takes into account all abiotic and biotic aspects For example, an organism’s habitat is one parameter used to describe the niche. Connections to the size of the acorn crop.

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Chapter 52

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  1. Chapter 52 Community Ecology

  2. Ecological niche • Distinctive lifestyle and role of an organism in a community • Takes into account all abiotic and biotic aspects • For example, an organism’s habitat is one parameter used to describe the niche

  3. Connections to the size of the acorn crop

  4. Fundamental niche • Potential ecological niche for an organism • Realized niche • Niche an organism actually occupies • Limiting resources • Environmental factors that restrict a realized niche

  5. Effect of competition on an organism’s realized niche

  6. Competition • Two or more individuals attempting to use the same resource • Intraspecific competition • Among individuals within a population • Interspecific competition • Between different species

  7. Interspecific competition

  8. Competitive exclusion principle • Two species cannot occupy the same niche in the same community for an indefinite period • One species is excluded by another as a result of competition

  9. Some species reduce competition by resource partitioning • Competition among species is reduced by character displacement • Structural ecological and behavioral characteristics diverge where ranges overlap

  10. Resource partitioning

  11. Predation • Consumption of one species (the prey) by another (the predator) • Coevolution • Predator and prey both evolve more efficient ways to interact

  12. Ecological interactions among species

  13. Defenses • Mechanical defenses • Associating in groups • Cryptic coloration • Warning coloration • Müllerian mimicry

  14. Cryptic coloration

  15. Symbiosis • Mutualism • Both partners benefit • Commensalism • One partner benefits and the other is unaffected • Parasitism • One partner benefits while the other is harmed

  16. Mutualism

  17. Commensalism

  18. Parasitism

  19. Keynote species • Present in small numbers but are crucial in determining the species composition and ecosystem functioning • Dominant species • Affect the community because they are so common

  20. Species richness • Number of species within a community • Species diversity • Relative importance of each species within a community

  21. Effect of community complexity on species richness

  22. Ecological succession • Primary succession • Occurs in an area not previously inhabited • Secondary succession • Occurs where there is a pre-existing community and well-formed soil

  23. Intermediate disturbance hypothesis • Disturbance affects succession and species richness • Species richness is greatest at moderate levels of disturbance

  24. Intermediate disturbance hypothesis

  25. The nature of communities • Organismic model • Views a community as a superorganism that goes through stages of development (succession) • Individualistic model • Abiotic environmental factors are primary determinants of species composition • Organisms are independent

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