Chapter 52 ecology overview class


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Chapter 52 ecology overview class

  1. 1. Chapter 52 An Introduction to Ecology and the Biosphere
  2. 2. Overview: The Scope of Ecology • Ecology – Is the scientific study of the interactions between organisms and the environment • These interactions – Determine both the distribution of organisms and their abundance – Is an enormously complex and exciting area of biology – Reveals the richness of the biosphere
  3. 3. Sub-fields of Ecology • Organismal ecology – Studies how an organism’s structure, physiology, and (for animals) behavior meet the challenges posed by the environment Figure 50.3a (a) Organismal ecology. How do humpback whales select their calving areas?
  4. 4. • Population ecology _ Population: groups of same species in the same area. – Concentrates mainly on factors that affect how many individuals of a particular species live in an area Figure 50.3b Population ecology. What environmental factors affect the reproductive rate of deer mice? (b)
  5. 5. • Community ecology - Community: all the organisms in one particular area. – Deals with the whole array of interacting species in a community Figure 50.3c (c) Community ecology. What factors influence the diversity of species that make up a particular forest?
  6. 6. • Ecosystem ecology - all the abiotic factors in addition to the entire commuity of species in a certain area. – Emphasizes energy flow and chemical cycling among the various biotic and abiotic components Figure 50.3d (d) Ecosystem ecology. What factors control photosynthetic productivity in a temperate grassland ecosystem?
  7. 7. • Landscape ecology – Deals with arrays of ecosystems and how they are arranged in a geographic region – Focuses on the factors controlling exchanges of energy, materials, and organisms among the ecosystem patches making up a landscape or seacape Figure 50.3e (e) Landscape ecology. To what extent do the trees lining the drainage channels in this landscape serve as corridors of dispersal for forest animals?
  8. 8. • The biosphere – Is the global ecosystem, the sum of all the planet’s ecosystems – Ex: How CO2 concentration affect the climate and all life on Earth. – Global ecology examines the influence of energy and materials on organisms across the biosphere
  9. 9. Concept 52.1: Ecology integrates all areas of biological research and informs environmental decision making • Ecology has a long history as a descriptive science • It is also a rigorous experimental science
  10. 10. Fig. 52-3 Trough Pipe “Dry” “Wet” “Ambient” Studying how a forest responds to altered precipitation
  11. 11. Ecology and Environmental Issues • Ecology – Provides the scientific understanding underlying environmental issues • Rachel Carson – Is credited with starting the modern environmental movement – Silent Spring, 1962 – DDT Figure 50.4
  12. 12. Ecology and Evolutionary Biology • Events that occur in ecological time – Affect life on the scale of evolutionary time – Therefore, ecology and evolutionary biology are closely related sciences. – Ex: haws deeding on field mice causing – Immediately effect: Reducing of the size of the mice population and altering the gene pool – Long-term effect: predator-prey interaction may be selected for mice with fur coloration that camouflages the animals.
  13. 13. Concept 52.2: Interactions between organisms and the environment limit the distribution of species • Ecologists have long recognized global and regional patterns of distribution of organisms within the biosphere. • Biogeography is a good starting point for understanding what limits geographic distribution of species. • Ecologists recognize two kinds of factors that determine distribution: biotic, or living factors, and abiotic, or nonliving factors.
  14. 14. Fig. 52-5 Kangaroos/km2 0–0.1 0.1–1 1–5 5–10 10–20 > 20 Limits of distribution
  15. 15. Fig. 52-6 Why is species X absent from an area? Does dispersal limit its distribution? Does behavior limit its distribution? Area inaccessible or insufficient time Yes No No No Yes Yes Habitat selection Do biotic factors (other species) limit its distribution? Predation, parasitism, competition, disease Do abiotic factors limit its distribution? Chemical factors Physical factors Water Oxygen Salinity pH Soil nutrients, etc. Temperature Light Soil structure Fire Moisture, etc. • Ecologists consider multiple factors when attempting to explain the distribution of species
  16. 16. • Concept 50.2: Interactions between organisms and the environment limit the distribution of species • Ecologists – Have long recognized global and regional patterns of distribution of organisms within the biosphere
  17. 17. Dispersal and Distribution • Dispersal – Is the movement of individuals away from centers of high population density or from their area of origin – Contributes to the global distribution of organisms
  18. 18. Fig. 52-7 Current 1966 1970 1965 1960 1961 1958 1951 1943 1937 1956 1970 Natural Range Expansions Dispersal of the cattle egret in the Americas
  19. 19. Species Transplants • Species transplants – Include organisms that are intentionally or accidentally relocated from their original distribution – Can often disrupt the communities or ecosystems to which they have been introduced – To be successful in species transplants, the organism must not only survive in the new area but also reproduce there.
  20. 20. Behavior and Habitat Selection • Some organisms – Do not occupy all of their potential range • Species distribution – May be limited by habitat selection behavior – Example: larvae of the European corn borer – Example: mosquito habitats
  21. 21. Biotic Factors • Biotic factors that affect the distribution of organisms may include – Interactions with other species – Predation – Competition
  22. 22. A specific case of an herbivore limiting distribution of a food species • Seaweed distribution Figure 52.8 W. J. Fletcher tested the effects of two algae-eating animals, sea urchins and limpets, on seaweed abundance near Sydney, Australia. In areas adjacent to a control site, either the urchins, the limpets, or both were removed. EXPERIMENT RESULTS Fletcher observed a large difference in seaweed growth between areas with and without sea urchins. 100 80 60 40 20 0 Limpet Sea urchin Both limpets and urchins removed Only urchins removed Only limpets removed August 1982 February 1983 August 1983 February 1984 Control (both urchins and limpets present) Seaweedcover(%) Removing both limpets and urchins or removing only urchins increased seaweed cover dramatically. Almost no seaweed grew in areas where both urchins and limpets were present, or where only limpets were removed. Removing both limpets and urchins resulted in the greatest increase of seaweed cover, indicating that both species have some influence on seaweed distribution. But since removing only urchins greatly increased seaweed growth while removing only limpets had little effect, Fletcher concluded that sea urchins have a much greater effect than limpets in limiting seaweed distribution. CONCLUSION
  23. 23. Biotic Factors for Limiting Distribution • Predation • Herbivory • Food sources • Parasites • Pathogens • Competing organisms
  24. 24. Abiotic Factors • Abiotic factors that affect the distribution of organisms may include – Temperature – Water – Sunlight – Wind – Rocks and soil
  25. 25. Climate • Four major abiotic components make up climate – Temperature, water, sunlight, and wind • Climate – Is the prevailing weather conditions in a particular area
  26. 26. Classification of Climate Factors • Climate patterns can be described on two scales – Macroclimate, patterns on the global, regional, and local level – Microclimate, very fine patterns, such as those encountered by the community of organisms underneath a fallen log
  27. 27. Global Climate Patterns • Earth’s global climate patterns – Are determined largely by the input of solar energy and the planet’s movement in space
  28. 28. Regional, Local, and Seasonal Effects on Climate • Various features of the landscape – Contribute to local variations in climate
  29. 29. Microclimate • Microclimate – Is determined by fine-scale differences in abiotic factors
  30. 30. Long-Term Climate Change • One way to predict future global climate change – Is to look back at the changes that occurred previously Figure 52.14 Current range Predicted range Overlap (a) 4.5C warming over next century (b) 6.5C warming over next century
  31. 31. • Concept 50.3: Abiotic and biotic factors influence the structure and dynamics of aquatic biomes • Varying combinations of both biotic and abiotic factors – Determine the nature of Earth’s many biomes • Biomes – Are the major types of ecological associations that occupy broad geographic regions of land or water
  32. 32. • The examination of biomes will begin with Earth’s aquatic biomes Figure 52.15 30N Tropic of Cancer Equator 30S Continental shelf Lakes Coral reefs Rivers Oceanic pelagic zone Estuaries Intertidal zone Abyssal zone (below oceanic pelagic zone) Key Tropic of Capricorn
  33. 33. • Aquatic biomes – Account for the largest part of the biosphere in terms of area – Can contain fresh or salt water • Oceans – Cover about 75% of Earth’s surface – Have an enormous impact on the biosphere
  34. 34. • Concept 50.4: Climate largely determines the distribution and structure of terrestrial biomes • Climate – Is particularly important in determining why particular terrestrial biomes are found in certain areas
  35. 35. General Features of Terrestrial Biomes • Terrestrial biomes – Are often named for major physical or climatic factors and for their predominant vegetation • Stratification – Is an important feature of terrestrial biomes
  36. 36. The distribution of major terrestrial biomes 30N Tropic of Cancer Equator Tropic of Capricorn 30S Key Tropical forest Savanna Desert Chaparral Temperate grassland Temperate broadleaf forest Coniferous forest Tundra High mountains Polar iceFigure 50.19
  37. 37. Climate and Terrestrial Biomes • Climate has a great impact on the distribution of organisms, as seen on a climograph Figure 50.18 Desert Temperate grassland Tropical forest Temperate broadleaf forest Coniferous forest Arctic and alpine tundra Annual mean precipitation (cm) Annualmeantemperature(ºC) 100 200 300 400 30 15 0 15