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Ecosystem Interactions

Ecosystem Interactions. Honors Biology Chapter 14. Where & how organisms live. Range- geographical reach. Habitat- where. Ecological Niche- how. Niche includes food, abiotic conditions, behavior. Competition results when species, in the same community, overlap in use of resources

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Ecosystem Interactions

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  1. Ecosystem Interactions Honors Biology Chapter 14

  2. Where & how organisms live Range- geographical reach Habitat- where Ecological Niche- how

  3. Niche includes food, abiotic conditions, behavior • Competition results when species, in the same community, overlap in use of resources • Strong selective force • Competitive exclusion • Banishment/extinction • Evolution • Niche partitioning

  4. Niche (resource) partitioning

  5. Ecological Equivalents – same niche…different communities Convergent evolution’s fingerprint

  6. Predation – Another interaction with highly selective outcomes

  7. Symbiosis – a kinder interaction, tho’ not without an evolutionary punch Mutualism – both benefit Commensalism – one benefits, the other unaffected Parasitism – parasite benefits, host harmed

  8. Population Dynamics • Population: all the individuals of a species that live together in an area • Demography: the statistical study of populations, make predictions about how a population will change

  9. Population Dynamics • Three Key Features of Populations • Size • Density • Dispersion • (spatial distribution)

  10. Three Key Features of Populations 1. Size: number of individuals in an area

  11. Influences on Population Size Survivorship Reproductive Strategies 1. R Strategists short life span, small body, reproduce quickly, many young, little parental care 2. K Strategists long life span, large body, reproduce slowly, few young, parental care,

  12. Three Key Features of Populations 2. Density: measurement of population per unit area or unit volume Formula: Dp= N/S Pop. Density = # of individuals ÷ unit of space

  13. Human Population Density

  14. Three Key Features of Populations 3. Dispersion: describes their spacing relative to each other • clumped • uniform • random

  15. Three Key Features of Populations Clumped for protection, resources, mating or social interaction Uniform dispersion due to intraspecies competition / territoriality 3. Dispersion: describes their spacing relative to each other Random dispersion implies absence of interaction - rare. Mature communities.

  16. Patterns of Dispersion

  17. Population Growth Patterns • Growth Rate: Birth Rate (natality) - Death Rate (mortality) • How many individuals are born vs. how many die • Birth rate (b) + Immigration rate (i) − death rate (d) = rate of natural increase (r). • Total Growth must add immigration & subtract emigration statistics

  18. Population Growth Patterns Exponential – J shaped curve Logistic – S curve

  19. Population Growth Patterns The “Boom Bust” Curve

  20. World Human Population Growth

  21. Other Factors Affecting Population Growth POST-REPRODUCTIVE REPRODUCTIVE PRE-REPRODUCTIVE Age Structure

  22. Age Demographics for Three Countries

  23. Estimated rates of US population growth with or without immigration. Immigration and Emigration Can Strongly Effect Population Dynamics Immigration & Emigration Influences on Total Rate of Growth

  24. Demographic TransitionThe move from “Developing” to “Developed” Country

  25. Other Factors Affecting Population Growth • Carrying Capacity-the maximum population size that can be supported by the available resources • There can only be as many organisms as the environmental resources can support

  26. J-shaped curve (exponential growth) Carrying Capacity Carrying Capacity (k) # S-shaped curve (logistic growth) Time

  27. Other Factors Affecting Population Growth • Limiting Factors - any biotic or abiotic factor that restricts the existence of organisms in a specific environment.

  28. Two Types of limiting Factors 1. Density-dependent factors- increase effect as population size increases. (disease, competition, parasites) 4. Density-independent factors-affecting populations regardless of their density (temperature, storms, habitat destruction, drought)

  29. Ecological Succession Succession after the Yellowstone fires. Succession at Mt. St. Helens. Gradual, sequential change in an area that regenerates or creates a community an area

  30. Primary succession: occurs where life has not previously existed Retreating Glaciers at Glacier Bay Alaska

  31. Primary Succesion – Very Slow

  32. Secondary Succession – Faster (soil already present) Mount St. Helens

  33. Succession Climax Community theoretical end-point of succession. Stable community.

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