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Chapter 50

Chapter 50. An Introduction to Ecology & the Biosphere. Overview: The Scope of Ecology. Ecology- study of interactions b/w organisms & environ These interactions determine distribution of organisms & their abundance Ecology reveals the richness of the biosphere.

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Chapter 50

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  1. Chapter 50 An Introduction to Ecology & the Biosphere

  2. Overview: The Scope of Ecology • Ecology- study of interactions b/w organisms & environ • These interactions determine distribution of organisms & their abundance • Ecology reveals the richness of the biosphere

  3. Concept 50.1: Ecology is the study of interactions b/w organisms & the environment • Ecology has a long history as a descriptive science • It is also a rigorous experimental science

  4. Ecology & Evolutionary Biology • Events that occur in ecological time affect life on the scale of evolutionary time

  5. Organisms & the Environment • The environment of any organism includes: • Abiotic- nonliving • Biotic- living • All organisms part of the indiv’s environment are collectively called the biota • Environmental components affect the distribution & abundance of organisms

  6. LE 50-2 Kangaroos/km2 > 20 10–20 5–10 1–5 0.1–1 < 0.1 Limits of distribution Tasmania

  7. Ecologists use observations & experiments to test explanations for the distribution & abundance of spp

  8. Subfields of Ecology • Organismal ecology- how an organism’s structure, physiology, & (for animals) behavior meet environmental challenges

  9. LE 50-3a Organismal ecology

  10. pop ecology- factors affecting how many indiv’s of a spp live in an area

  11. LE 50-3b pop ecology

  12. Community ecology- deals w/ interacting spp in a community

  13. LE 50-3c Community ecology

  14. Ecosystem ecology- emphasizes energy flow & chemical cycling for biotic & abiotic factors

  15. LE 50-3d Ecosystem ecology

  16. Landscape ecology- arrays of ecosystems & how they are arranged in a geographic region

  17. LE 50-3e Landscape ecology

  18. The biosphere is the global ecosystem, the sum of all the planet’s ecosystems

  19. Ecology & Environmental Issues • Ecology provides the scientific understanding underlying environmental issues • Rachel Carson is credited w/ starting the modern environmental mvmt

  20. Most ecologists follow the precautionary principle regarding environmental issues • It states that humans need to be concerned w/ how their actions affect the environment

  21. Concept 50.2: Interactions b/w organisms & the environment limit the distribution of spp • Ecologists have long recognized global & regional patterns of distribution of organisms within the biosphere • Many naturalists began to identify broad patterns of distribution by naming biogeographic realms

  22. LE 50-5 Palearctic Nearctic Tropic of Cancer (23.5°N) Oriental Ethiopian Equator Neotropical (23.5°S) Tropic of Capricorn Australian

  23. Biogeography is a good starting point for understanding what limits geographic distribution of spp

  24. LE 50-6 spp absent b/c Area inaccessible or insufficient time Yes Yes Dispersal limits distribution? Habitat selection Yes Predation, parasitism, competition, disease Chemical factors Behavior limits distribution? No Biotic factors (other spp) limit distribution? Water Oxygen Salinity pH Soil nutrients, etc. No Abiotic factors limit distribution? No Tm Light Soil structure Fire Moisture, etc. Physical factors

  25. Dispersal & Distribution • Dispersal- mvmt of indiv’s away from centers of high pop density or from their area of origin • Dispersal contributes to global distribution of organisms

  26. Natural Range Expansions • Natural range expansions show the influence of dispersal on distribution

  27. LE 50-7 New areas occupied Year 1996 1989 1974

  28. spp Transplants • spp transplants include organisms that are intentionally or accidentally relocated from their original distribution • spp transplants can disrupt the communities or ecosystems to which they have been introduced

  29. Behavior & Habitat Selection • Some organisms do not occupy all of their potential range • spp distribution may be limited by habitat selection behavior

  30. Biotic Factors • Biotic factors that affect the distribution of organisms: • Interactions w/ other spp • Predation • Competition

  31. LE 50-8 100 Sea urchin Both limpets & urchins removed 80 Only urchins removed 60 Seaweed cover (%) Limpet 40 Only limpets removed Control (both urchins & limpets present) 20 0 August 1982 February 1984 August 1983 February 1983

  32. Abiotic Factors • Abiotic factors affecting distribution of organisms: • Tm • Water • Sunlight • Wind • Rocks & soil

  33. Tm • Environmental Tm is an important factor in distribution of organisms b/c of its effects on biological processes

  34. Water • Water availability in habitats is another important factor in spp distribution

  35. Sunlight • Light intensity & quality affects photosynthesis • Light is also important to development & behavior of organisms sensitive to photoperiod

  36. Wind • Wind amplifies effects of Tm by increasing heat loss from evaporation & convection • Wind can change morphology of plants

  37. Rocks & Soil • Many chara’s of soil limit distribution of plants & so animals that eat them: • Physical structure • pH • Mineral composition

  38. Climate • 4 major abiotic components of climate: Tm, water, sunlight, & wind • Climate is the prevailing weather in an area • Macroclimate- patterns on the global, regional, & local level • Microclimate- fine patterns, such as those encountered by the community of organisms underneath a fallen log

  39. Global Climate Patterns • Global climate patterns are determined largely by solar energy & the planet’s mvmt in space

  40. Sunlight intensity plays a major part in determining the Earth’s climate patterns

  41. LE 50-10a North Pole 60°N Low angle of incoming sunlight 30°N Tropic of Cancer Sunlight directly overhead at equinoxes 0° (equator) Tropic of Capricorn 30°S Low angle of incoming sunlight 60°S South Pole Atmosphere

  42. Seasonal variations of light & Tm increase steadily toward the poles

  43. LE 50-10b March equinox: Equator faces sun directly; neither pole tilts toward sun; all regions on Earth experience 12 hours of daylight & 12 hours of darkness. 60°N 30°N June solstice: Northern Hemisphere tilts toward sun; summer begins in Northern Hemisphere; winter begins in Southern Hemisphere. 0° (equator) 30°S December solstice: Northern Hemisphere tilts away from sun; winter begins in Northern Hemisphere; summer begins in Southern Hemisphere. Constant tilt of 23.5° September equinox: Equator faces sun directly; neither pole tilts toward sun; all regions on Earth experience 12 hours of daylight & 12 hours of darkness.

  44. Global air circulation & wind patterns play major roles in determining climate patterns

  45. LE 50-10c 60°N 30°N Descending dry air absorbs moisture Descending dry air absorbs moisture 0° (equator) Ascending moist air releases moisture 30°S 60°S 0° 23.5° 23.5° 30° 30° Arid zone Arid zone Tropics

  46. LE 50-10d Arctic Circle 60°N Westerlies 30°N Northeast trades Doldrums 0° (equator) Southeast trades 30°S Westerlies 60°S Antarctic Circle

  47. Regional, Local, & Seasonal Effects on Climate • Various features of the landscape contribute to local variations in climate • Seasonal variation also influences climate

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