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Chapter 4

Chapter 4. Environments and Life Sir David Ochieng www.davidochieng.net. What is your current classification?. Freshman Sophomore Junior Senior. Guiding Questions. What factors determine the ecological niches of species, and by what means do species obtain nutrition?

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Chapter 4

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  1. Chapter 4 Environments and Life Sir David Ochieng www.davidochieng.net

  2. What is your current classification? • Freshman • Sophomore • Junior • Senior

  3. Guiding Questions • What factors determine the ecological niches of species, and by what means do species obtain nutrition? • What factors govern the geographic distribution of species? • What factors govern the distribution of aquatic life?

  4. Environmental Differences • Tropical vs Polar - Terrestrial and Marine • Low vs High Elevation • Shallow vs Deep • Wet vs Dry

  5. Hypsometric Curve • Curve showing the proportions of the Earth’s surface above and below sea level

  6. Hypsometric Curve

  7. Climate • Climate • Controls distribution of species globally • Has changed through time • Plate tectonics and other changes affect climate

  8. Ecology • Ecology • Study of the factors that govern the distribution and abundance of organisms in natural environments • Habitats • Environments on or close to Earth’s surface inhabited by life • Terrestrial • Aquatic • Marine • Freshwater

  9. Ecology • Ecologic niche • The way a species relates to its environment, including food, nutrients, physical and chemical conditions • Life habit • The way a species lives within its niche • Limiting factors • Naturally occurring, restricting condition (physical and chemical) • Competition • Shared drive for limited resources • Predation

  10. Competition Arises because organisms share space Predation also comes in here by possibly limiting or preventing another species from inhabiting a particular environment.

  11. Ecosystem • Ecosystem • Organisms of a community and the physical environment they occupy • Population • Group of individuals that belong to a single species and live together in a particular area

  12. Ecosystem • Ecologic community • Populations of several species living in a habitat • Producers • Photosynthesizing organisms; foundation of community • Consumers • Herbivores: feed on producers • Carnivores: feed on other consumers

  13. Ecosystem • Biota • Fauna: animals and protozoans of an ecosystem • Flora: plants and plantlike protists • Food chain • Sequence of consumption for producers to consumers

  14. Food Web • Food web • More complex than simple food chain • More common • Several species occupy each level

  15. Ecosystem • Parasites • Feed on living organisms • Scavengers • Feed on organisms that are already dead

  16. Ecology The movement of materials through an ecosystem. Components within ovals are consumers.

  17. Figure 4-35 (p. 134)Interdependence of photosynthesis and respiration.

  18. Figure 4-38 (p. 136)Simple pyramid of ocean life.

  19. Biogeography The distribution and abundance of organisms on a broad geographic scale.

  20. Biogeography • Temperature • Moisture • Nutrients

  21. Ecosystem • Diversity • The variety of species that live together within a community • Lower in more difficult habitats • Predation influences diversity • Heavy can reduce diversity • Moderate can increase diversity by reducing competition • Opportunistic species • Species that specialize in invading newly vacated habitats

  22. Biogeography • Distribution and abundance of organisms on a broad geographic scale • Limiting factors • Diversity increases toward equator • Barriers can affect dispersal

  23. Life Habitats The mode by which an organism lives, feeds in an environment 1. Tropical vs. Polar 2. Low vs high altitude 3. Shallow vs deep 4. Benthic vs. Planktonic

  24. Atmosphere • Regulates Earth’s temperature (-18°C w/o atmosphere) • Composition • N2, O2, CO2 • Tilt of the Earth affects solar insulation, temperature, and climate

  25. In our present atmosphere, concentrations of O2 and CO2 are: • O2 > CO2 • O2 < CO2 • O2 = CO2

  26. The Atmosphere • Nitrogen -78% • Oxygen - 21% • Carbon dioxide (CO2 ) - 0.037% or 370 ppm • Methane (CH4) - 0.00018% or 1800 ppb

  27. Solar Radiation Daylight Which receives more hours of daylight? Equator vs Poles The amount of daylight (# of hours) averaged over a year is the same at the poles as at the equator

  28. Solar Radiation

  29. Solar Radiation • Temperature difference is due to the angle of the sunlight and the albedo • In the high latitudes, the sun hits at a low angle and therefore the unit energy of sunlight is spread over a large cross-sectional area of the earth’s surface. In the tropics, the sun hits directly and therefore is much more concentrated

  30. Solar Radiation

  31. Solar Radiation Albedo refers to the reflectivity of the Earth’s surface 1. Snow and ice is very reflective - much of the solar radiation is reflected by to the solar system 2. Water has a low albedo and absorbs a lot of the solar radiation

  32. Solar Radiation

  33. Solar Radiation

  34. Solar Radiation • When do we have summers? • True or False • Summers on Earth occur when it passes closest to the Sun

  35. Solar Radiation • Obliquity or Tilt (23.5°) of the to Earth’s rotational axis • This tilt gives us seasons. Summer is when the northern or southern hemisphere is point towards the Sun

  36. Atmosphere • Regulates Earth’s temperature • Composition • N2, O2, CO2 • Tilt of the Earth affects solar insulation, temperature, and climate

  37. Solar RadiationHeat Capacity

  38. Movement of Air mass • Rises at Eq. and sinks near Poles • The high solar radiation at the equator heats the air masses, causing them to rise (buoyant). • As the air rises, the temperature of the air mass decreases

  39. Atmospheric Circulation • Net transport • Air sinks at the poles, rises at the equator • Simplified model • No tilt • No Coriolis effect

  40. Rising Air As the air rises, the temperature of the air mass decreases (adiabatic lapse rate 5°C/km) Cold air holds less water vapor. Voila, rain and the tropical rainforest. Low pressure systems usually have rain because the rising air drop water as the air ascends and cools

  41. Rising Air

  42. Atmospheric Circulation • Coriolis effect • Earth’s rotation causes air and water masses to be defected to the right (clockwise) in the northern hemisphere • Counterclockwise for southern hemisphere

  43. Atmospheric Circulation • If we reverse the direction and launch a rocket from Panama towards Washington DC, which way will it curve? • A = Right • B = Left • C = Not at all because Panama is close to the Eq.

  44. Coriolis force • Deflection of moving objects to the right in the No. Hemisphere and left in the So. Hemisphere

  45. Coriolis Force

  46. Atmospheric Circulation • Actual pattern is more complex • Three circulation cells • Trade winds, westerlies, easterlies • Intertropical convergence zone • Northern, southern trade winds converge near equator • Changes seasonally

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