Geology MT2 pt 2

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Geology MT2 pt 2
2013-05-19 14:22:33

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  1. Ecological biogeography
    • geographic distribution of organisms
    • largely descriptive - who lives where?
  2. Diversity
  3. Abundance
    # individuals
  4. Simpson coefficient
    (Number of species common to both samples)/(number of species in less diverse sample) *100
  5. Jaccard coefficient
    (#species common to both samples)/(#species in less diverse sample + #species in more diverse sample - #species common)

    1.00 means identical
  6. Cosmopolitan species
    world-wide, with broad biogeographical distribution (e.g., humans)
  7. Endemic species
    • restricted to a single region (e.g. lemurs in Madagascar)
    • young: e.g., in Hawaii; islands are geologically young, so species originating there haven't had time to move elsewhere
    • relict: former range was much wider, now restricted to a single (or few) region -> need fossil record to detect
  8. Disjunct species
    in 2 or more regions, now widely separated
  9. Modern controls on geographic distribution
    • Atmospheric/oceanic circulation
    • Climate, continental position
  10. Atmospheric and oceanic circulation
    • seasonality: light and heat from sun varies latitudinally and throughout year
    • Equator: sunlight strikes at higher angle ->warmer; warm air rises and can hold more moisture
    • 3 main gyres (rotating ocean current), equator to poles: trade winds, westerlies, easterlies
    • wind and patterns of atmospheric circulation determine patterns of oceanic circulation
  11. Climate and continental position
    • Continents perturb broad patterns of circulation->upwelling (wind-driven motion of dense, cooler, nutrient-rich water towards ocean surface) may develop on continental margins (CA); altitude disturbs wind, causes rain shadows
    • Continental size affects circulation; larger land masses have more highly seasonal climates than small land masses
  12. Upwelling
    denser, cooler water moves to surface (by wind)
  13. Rain shadows
    an area of dry land that lies on the leeward (or downwind) side of a mountain. Winds carry air masses up and over the mountain range and as the air is driven upward over the mountain, falling temperatures cause the air to lose much of its moisture as precipitation. Upon reaching the leeward side of the mountain, the dry air descends and picks up any available moisture from the landscape below
  14. Can explain biomes and provinces by variations in?
    • Temperature
    • precipitaton
    • light
  15. Historical biogeography
    • how organisms got where they are today
    • dispersal
    • vicariance
  16. Dispersal
    • Expansion of contraction of biogeographic locations over generations
    • Active movement of organisms
    • Passive movement (fluid environment)
  17. Barriers
    • limits to dispersal, related to body size
    • physiological, physical, ecological (e.g. high mountain ranges, oceans, deserts)
    • can change over an org's lifetime, or over geological time (species range)
    • some individuals can cross, some can't->biogeographic isolation
    • doesn't explain disjunct distributions
    • continental drift
  18. Plate tectonics
    • heat-driven convection cells are generated in mantle
    • crust (relatively brittle) broken into plates that interact with one another by spreading, subduction, transform (sliding)
    • continental drift affects oceanic circulation and climate
    • climate: relativity to poles, size of landmass
    • explanation of disjunct distributions
  19. Vicariance Biogeography
    Fragmentation of largeareas into smallerones by introduction of non-biological barriers, or accretion of smaller areas into larger areas

    • Moving contents move organisms along passively
    • Noah's Ark: living orgs carried passively (e.g. India)
    • Beached Viking funeral ships: fossil organisms carried along with land
    • Escalator hopscotch: living orgs hop from one island to the next. Eg Hawaiian islands
  20. Analysis of vicariance biogeography
    • Conduct phylogenetic analysis with morphology and/or molecular sequence data
    • Translate phylogenetic hypothesis into branching pattern of area relationships
    • Test with phylogenetic/area cladograms for other orgs
    • Investigate non-biological (usually geological) events that produce a similar pattern
  21. Corridors
    • relatively unobstructed routes of dispersal (terrestrial)
    • Wooly mammoth 350-10k years ago, Bering land bridge
  22. Evolutionary Paleogeography
    • Tectonic Fragmentation and species diversity
    • Great American Biotic Interchange
    • Larval ecology, geographic range, speciation rate
    • Latitudinal diversity gradients
  23. Tectonic fragmentation and species diversity
    • Species diversity and size of geographic region
    • land mass is proportional to #species supported
    • splitting of continents causes geographic isolation (allopatry but bigger), habitat diversity
    • highest species diversity will be generated at times when continents are most fragmented; smaller areas able to support smaller standing diversity
  24. Great American Biotic Interchange
    • North and South America are linked by Central America (weren't before)
    • endemic fauna  for 50million years
    • in late Pliocene (3-5mya), major fauna among terrestrial vertebrates
    • isthmus: corridor for terrestrial orgs, barrier for marine orgs
  25. Larval ecology, geographic range, speciation rate
    • Planktotrophs: feeding larvae
    • in water: longtime
    • dispersal capabilities excellent
    • geographic ranges broader
    • stratigraphic ranges longer
    • speciation rates lower

    • Lecithotrophs: non-feeding larvae
    • in water: short time
    • dispersal capabilities limited
    • geographic ranges narrower
    • stratigraphic ranges shorter
    • speciation rates higher
  26. Latitudinal diversity gradients (terrestrial+marine)...hypotheses
    Species diversity increases toward the equator, decreases toward poles (since Paleozoic era)

    • hypotheses:
    • -tropics older; more sable and predictable habitats, richer in resources
    • -tropics as "cradle"'; more species appear in tropics than temperate regions
    • -tropics as "museum"; more species appear in temperate zone, but higher diversity can be maintained in tropics
  27. stratigraphic range
    • known occurrence of a fossil in stratigraphic record
    • beginning at FAD ending at LAD
    • high rates of evolution=short stratigraphic ranges
    • low rates of evolution=long stratigraphic ranges
  28. assemblage
    • group of co-occurring species
    • characterize zones
  29. Event stratigraphy
    • distinctive chemical signature or sedimentary feature
    • used to correlate more broadly
  30. index fossils
    • distinctive type of zone fossil
    • wide geographic dist
    • short vertical(stratigraphic) dist
    • distinct mo0rphological characteristics
    • hard, mineralized skeletons
    • abundant, easily found
  31. Biases
    • generalist taxa: live in a  wide range of environmental habitats;
    • specialist taxa: restricted habitats
    • cosmopolitan taxa have broad geographic ranges
    • endemic taxa: narrower geographic ranges