1. 1 Chapter 4 Environments and Life

2. 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?

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4. 4 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

5. 5 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

6. 6 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

7. 7 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

8. 8 Ecosystem Biota –Fauna: animals and protozoans of an ecosystem –Flora: plants and plantlike protists Food chain –Sequence of consumption for producers to consumers

9. 9 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

10. 10 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

11. 11 Biogeography Limiting factors –Diversity increases toward equator –Barriers can affect dispersal Distribution and abundance of organisms on a broad geographic scale

12. 12 Atmosphere Regulates Earth’s temperature Composition –N 2, O 2, CO 2 Tilt of the Earth affects solar insulation, temperature, and climate

13. 13 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

14. 14 Atmospheric Circulation Net transport –Air sinks at the poles, rises at the equator –Simplified model No tilt No Coriolis effect

15. 15 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

16. 16 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

17. 17 Terrestrial Realm Vegetation follows climatic zone –Tropical rain forest –Desert savannahs –Temperate forests –Polar tundra

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

19. 19 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

20. 20 Terrestrial Realm Poles –Defined by ice sheets and glaciers today –Absent or reduced at times in the past

21. 21 Terrestrial Realm Glaciers –Ice in motion –Glide and spread –Present at high latitudes and high elevations near equator

22. 22 Terrestrial Realm Tundra –Limited water –Grasses, sedges, lichens, shrubs dominate –Cannot support tall trees Evergreen coniferous forests –South of tundra –Spruce, pine, fir

23. 23 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

24. 24 Climate –Controls distribution of species globally –Has changed through time Plate tectonics and other changes affect climate

25. 25 Climate Altitude –Similar to latitudinal gradient –At base Deciduous forest –On slopes Evergreen forest Tundra above tree-line –At top Glaciers

26. 26 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

27. 27 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

28. 28 Plants as Climate Indicators Sensitive indicators of change –Cycads Tropics and subtropics today Fossil distribution allows reconstruction of climate patterns

29. 29 Plants as Climate Indicators Leaf Margins –Tropics Smooth, waxy margins –Temperate climates Jagged margins

30. 30 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

31. 31 Marine Realm Circumpolar current –Circles Antarctica –Very cold

32. 32 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

33. 33 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

34. 34 Marine Realm Continental Shelf –Submarine extension of continental landmass Shelf break –Edge of shelf ~200 m w.d. Continental Slope Continental Rise Abyssal Plain

35. 35 Marine Realm Near shore –Barrier islands –Marshes –Epicontinental seas

36. 36 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

37. 37 Marine Realm Marine Biogeography –Tropical –Subtropical –Transitional –Subarctic

38. 38 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

39. 39 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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