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Population & Community Ecology:

Population & Community Ecology:. Thursday 12 /7/ 13. population structure & growth limitations on growth // natural fluctuations community ecology properties of a community interspecific interactions competition symbiotic relationships Ecological Succession

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Population & Community Ecology:

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  1. Population & Community Ecology: Thursday 12/7/13 • population structure & growth • limitations on growth // natural fluctuations • community ecology • properties of a community • interspecific interactions • competition • symbiotic relationships • Ecological Succession • stability - response to disturbances • Quiz on Tuesday – 10pts • will cover today’s lecture (overlaps with lab) • will be able to use notes

  2. Population ecology • & causes of these changes

  3. Population Growth - how population size changes over time fig 34.3 Exponential growth -- Logistic growth -

  4. Population Growth - • what factors influence growth? G = r = N = K =

  5. Carrying Capacity: • # of individuals an environment can support fig 34.3 Environmental resistance: -

  6. Natural fluctuations in population size: • most long-term studies show population size determined by multiple factors • key selective factor • long-term studies are key

  7. Ecological Footprint: • amount of land needed to “support” individuals • what demands are being placed on resources Human Population Growth: • exponential growth • “unlimited” resources • impact on environment? • can growth continue?

  8. Human population growth varies with countries: see fig 34.5 • growth rate • populations may still be • less developed countries Fig 34.6

  9. Limits on Population Growth: • Density-dependent: • biotic factors • greater impact w/ higher densities • resource limitations • predation / disease

  10. Limits on Population Growth: • Density-independent effects: • affect populations regardless of density • major increases • examples: • these may also be

  11. Competitive Exclusion: two organisms competing for one species will can not survive Ecological niche: fig 34.8

  12. Ecological Niche & Competition fig 34.9 Fundamental niche: Realized niche: Two species of barnacles Chthamalus is outcompeted in area of competition and realized niche is less than the fundamental niche

  13. resource partitioning • if intense competition --> • subdividing niche -- • seen in

  14. Character Displacement • sympatric species tend to show • differences favored by natural selection • when in sympatry- • when in allopatry–

  15. Co-evolution & Symbiosis • Symbiotic Relationships • Co-evolution • evolution of traits/behaviors

  16. mutualism (+/+) • examples: mycorrhizae / plants • ants & acacia trees

  17. parasitism (+/-) • an interspecific interaction • parasites rarely kill their hosts

  18. Predator-Prey interactions (+/-): • predator consumes prey • predators impact on community varies -- • no direct impact on population size -- • maintaining population sizeof prey species – • reducing population size -

  19. Adaptation of animal predators: Plant and Animal Defenses • Adaptation of herbivores

  20. Plant and Animal Defenses • adaptations of prey species: • plants: • animals:

  21. Defenses & Counter-defenses: • mimicry • Mullerian mimicry • ex: • Batesian mimicry • ex: stinging insects – Mullerianmimcs fig 34.12 non-stinging insects – Batesianmimcs Pipevine – toxic // Red-spotted - non-toxic

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