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Exploring Ecological Niches and Geographic Distribution in Ecology

Learn about factors shaping species niches, obtaining nutrients, geographic distributions, aquatic life, and ecological communities. Understand ecosystems, population dynamics, food chains, diversity, biogeography, and climate influences.

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Exploring Ecological Niches and Geographic Distribution in Ecology

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  1. Chapter 4 Environments and Life

  2. 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?

  3. 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

  4. 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

  5. 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

  6. 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

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

  8. Ecosystem • Food web • More complex than simple food chain • More common • Several species occupy each level • Parasites • Feed on living organisms • Scavengers • Feed on organisms that are already dead

  9. 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

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

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

  12. 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

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

  14. 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

  15. Temperature Variations • Atmosphere retains heat • Solar radiation • Absorbed and turned into heat energy • Reflected • 6-10% ocean • 5-30% forest • 45-95% ice and snow

  16. Terrestrial Realm • Vegetation follows climatic zone • Tropical rain forest • Desert savannahs • Temperate forests • Polar tundra

  17. Terrestrial Realm • Tropical Climates • 18–20° C (64–68° F) • 0–30° latitude • Tropical Rain Forest • Dense vegetation

  18. Terrestrial Realm • Deserts • Dry trade winds remove moisture • 20–30° north and south of the equator • < 25 cm rain/year • Little vegetation • Savannah, grasslands • Too dry to support forests

  19. Terrestrial Realm • Poles • Defined by ice sheets and glaciers today • Absent or reduced at times in the past

  20. Terrestrial Realm • Glaciers • Ice in motion • Glide and spread • Present at high latitudes and high elevations near equator

  21. Terrestrial Realm • Tundra • Limited water • Grasses, sedges, lichens, shrubs dominate • Cannot support tall trees • Evergreen coniferous forests • South of tundra • Spruce, pine, fir

  22. Terrestrial Realm • Temperate forests • Longer summers, slightly warmer • Deciduous trees • Maples, oaks, beeches • Mediterranean climate • Dry summers, wet winters • Common 40° N and S of equator • Californian, Mediterranean region

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

  24. Climate • Altitude • Similar to latitudinal gradient • At base • Deciduous forest • On slopes • Evergreen forest • Tundra above tree-line • At top • Glaciers

  25. Climate • Mountains • Rain shadow • Prevailing winds bring moisture • Precipitation on windward side • Aridity on leeward side • Rain shadows common on east side of North American mountain chains

  26. Climate • Seasonal Change • High heat capacity of water • Less change in ocean temperatures than on land • Monsoon Circulation • Summer winds flow onshore; bring rain • Winter winds offshore

  27. Plants as Climate Indicators • Sensitive indicators of change • Cycads • Tropics and subtropics today • Fossil distribution allows reconstruction of climate patterns

  28. Plants as Climate Indicators • Leaf Margins • Tropics • Smooth, waxy margins • Temperate climates • Jagged margins

  29. Marine Realm • Ocean currents • Wind driven • Follow atmospheric patterns • Trade winds • Push waters west; form equatorial currents • Equatorial countercurrents • Return flow • Gyres • Clockwise in Northern Hemisphere • Gulf Stream

  30. Marine Realm • Circumpolar current • Circles Antarctica • Very cold

  31. Marine Realm • Polar circulation • Sea ice leads to more saline water • Cold, dense waters sink • Antarctic waters • Flow north at depth • Arctic waters • Flow south at depth

  32. Marine Realm • Ocean circulation • Waves • Surface waves • Wind driven • Break when seafloor interacts at shallow depths • Tides • Cause major movement of water in oceans • Due to rotation of solid Earth beneath bulges of water produced by gravitational attraction of the moon

  33. Marine Realm • Continental Shelf • Submarine extension of continental landmass • Shelf break • Edge of shelf • ~200 m w.d. • Continental Slope • Continental Rise • Abyssal Plain

  34. Marine Realm • Near shore • Barrier islands • Marshes • Epicontinental seas

  35. Marine Realm • Photic Zone • Region of ocean where enough light penetrates to permit photosynthesis • Pelagic life • Plankton • Phytoplankton • Zooplankton • Nekton • Benthic life • Suspension feeders • Deposit feeders

  36. Marine Realm • Marine Biogeography • Tropical • Subtropical • Transitional • Subarctic

  37. Marine Realm • Corals • Most require warm water • Common in tropics • Reef builders • Coral polyp • Builds coral cup • Connected to other polyps • Symbiotic relationship with algae

  38. Marine Realm • Salinity • Limiting factor near shore • Oceanic • 35 ppt • Brackish • Lower than marine • Bays, lagoons • Hypersaline • Higher than marine • Hot arid climates

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