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The%20Biosphere%20and%20Animal%20Distribution

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Title: The%20Biosphere%20and%20Animal%20Distribution


1
The Biosphere and Animal Distribution
  • Chapter 37

2
Earth Environment - Overview
  • Water has physical properties critical to life on
    earth.
  • The steady supply of sunlight maintains a
    suitable range of temperatures for life
    metabolism.
  • Living matter requires a supply of major and
    minor elements available on earth.
  • The earths gravity is strong enough to hold an
    extensive gaseous atmosphere.

3
Earth Environment
  • The environment is modified by organisms.
  • Organisms are adapted by evolution to the
    environment.
  • The earth is an open system with a continuous
    supply of energy.
  • Building materials for life come from producers
    and are cycled through consumers.
  • Life is part of a cycle of life-death-decay-recycl
    ing.

4
Earth Environment
  • The primitive earth of 4.5 billion years ago had
    a reducing atmosphere of ammonia, methane, and
    water and was fit for pre-biotic synthesis of
    early living forms.
  • This early atmosphere would be fatal to todays
    organisms.
  • The appearance of free oxygen in the atmosphere
    is an example of the reciprocity of life and the
    earth.
  • Living organisms produce changes in their
    environment and must adapt and evolve.

5
Biosphere
  • The biosphere is the thin outer layer of the
    earth capable of supporting life.
  • Includes living organisms as well as the physical
    environments.

6
Biosphere - Subdivisions
  • Lithosphere rocky material of the earths outer
    shell.
  • Source of mineral elements required for life.
  • Hydrosphere water on or near the earths
    surface.
  • Atmosphere the gaseous component of the
    biosphere.
  • Atmospheric oxygen is produced by photosynthesis.

7
Greenhouse Effect
  • Materials in the atmosphere, such as CO2 and
    water vapor retain heat, raising atmospheric
    temperature.
  • Greenhouse effect
  • Burning fossil fuels increases CO2 in the
    atmosphere.

8
Greenhouse Effect
  • The greenhouse effect provides conditions
    essential for life on Earth.
  • Humans are increasing this effect.
  • Increased temperatures could lead to a rise in
    sea level as polar ice melts.

9
Biomes
  • Varying combinations of both biotic and abiotic
    factors determine the nature of Earths many
    biomes.
  • Biomes are the major types of ecological
    associations that occupy broad geographic regions
    of land or water.

10
Biomes
  • Each biome grades into the next without sharp
    boundaries.
  • Boundary areas are called ecoclines.

11
Terrestrial Biomes
  • Climate is particularly important in determining
    why particular terrestrial biomes are found in
    certain areas.
  • Temperature
  • Rainfall
  • Solar radiation

12
Terrestrial Biomes
  • The suns rays strike higher latitudes at a lower
    angle.
  • Atmospheric heating is less.

13
Terrestrial Biomes
  • Air warmed at the equator rises and moves toward
    the poles.
  • Replaced by cold air moving away from the poles.
  • Rotation of the earth complicates this pattern.
  • Three latitudinal cells result.

14
Terrestrial Biomes
  • Hot, moist air rises at equator, cools, condenses
    and provides rainfall (tropical forests).
  • Warm air flows northward, and sinks at 20-30
    latitude dry.
  • Air heats, absorbs moisture (desert areas), then
    the air flows toward the equator again.

15
The Distribution of Major Terrestrial Biomes
16
General Features of Terrestrial Biomes
  • Vertical stratification is an important feature
    of terrestrial biomes.
  • Canopy
  • Low-tree
  • Shrub understory
  • Ground layer
  • Forest floor (litter layer)

17
Temperate Deciduous Forest
  • Temperate deciduous forests receive rain
    year-round.
  • Cold winters and hot, humid summers.
  • Animals may migrate, hibernate, or survive on
    scarce available food or stored fat through the
    winter.

18
Coniferous Forest
  • Coniferous forests, or taiga, are common in the
    northern hemisphere.
  • Evergreens dominant
  • Colder, less rain than temperate forests.

19
Coniferous Forest
  • Mammals that inhabit coniferous forests include
    deer, moose, elk, snowshoe hares, wolves, foxes,
    lynxes, weasels, bears.
  • Adapted for long, snowy winters.

20
Tropical Forest
  • Tropical rain forests receive lots of rain and
    are generally warm year-round.
  • Stratified
  • Diverse

21
Tropical Forest
  • Canopy insectivorous birds and bats fly above
    the canopy.
  • Fruit bats, canopy birds, and mammals live in the
    canopy eating leaves fruit.
  • Middle zones are home to arboreal mammals
    (monkeys, sloths), birds, bats, insects,
    amphibians.
  • Climbing animals move along the tree trunks
    feeding at all levels.
  • Ground level contains larger mammals (capybara,
    paca, agouti, pigs) as well as a variety of
    reptiles and amphibians.

22
Tropical Forest
  • Nutrients in a tropical forest are tied up in
    living organisms.
  • Soil is poor.
  • Slash and burn agriculture involves removing
    vegetation to grow crops but the soil is so
    poor that the fields must be moved often.

23
Grassland
  • Temperate grasslands receive seasonal
    precipitation and have cold winters and hot
    summers.
  • Prairie

24
Grassland
  • Grasses and herds of large grazing mammals are
    dominant.
  • Jackrabbits, prairie dogs, and ground squirrels
    are common.
  • Predators include coyotes, cougars, bobcats,
    raptors, badgers, and ferrets.

25
Grassland
  • Savannas are tropical grasslands with seasonal
    rainfall.

26
Grassland
  • Chaparral receives highly seasonal rainfall.
  • Shrubs and small trees are common.
  • Adaptations to fire.

27
Tundra
  • Tundra has a permanently frozen layer of soil
    called permafrost that prevents water
    infiltration.
  • Very cold, short growing season.
  • Little rain

28
Tundra
  • Tundra is often covered with bogs, marshes, or
    ponds.
  • Grasses, sedges, and lichens may be common.
  • Lemmings, caribou, musk-oxen, arctic foxes,
    arctic hares, ptarmigans and other migratory
    birds.

29
Desert
  • Deserts have very low precipitation less than
    30 cm/yr.
  • Variable temperatures.
  • Animals often nocturnal and live in burrows.
  • Reptiles and small mammals are common.

30
Aquatic Biomes
31
Aquatic Biomes
  • Aquatic biomes account for the largest part of
    the biosphere in terms of area.
  • Can contain fresh or salt water.
  • Oceans cover about 75 of Earths surface.
  • Have an enormous impact on the biosphere.

32
Inland Waters
  • Only about 2.5 of the earths water is fresh.
  • Much of that is found in polar ice caps or
    underground aquifers.

33
Inland Waters
  • Lotic, or running water habitats include streams
    and rivers.
  • More oxygen
  • Lentic, or standing water habitats include lakes
    and ponds.
  • Less oxygen

34
Inland Waters
LAKES
  • Oligotrophic lakes nutrient poor oxygen rich.
  • Eutrophic lakes nutrient rich sometimes
    oxygen poor.
  • Eutrophication

An oligotrophic lake
A eutrophic lake
35
Inland Waters
STREAMS AND RIVERS
  • Streams and rivers have a current.

36
Inland Waters
  • Animals living in vegetation or debris of the
    bottom (benthos) are called benthic.
  • Snails, mussels, crustaceans, insects.
  • Animals up in the water column are pelagic.
  • Swimming animals are called nekton.
  • Floating or weak swimmers are called plankton.

37
Wetlands
WETLANDS
  • Wetlands include areas that are able to support
    aquatic plants.
  • May be freshwater or marine.

38
Estuaries
ESTUARIES
  • Estuaries are transition areas between river and
    sea.
  • Salinity varies from nearly fresh to the salinity
    of seawater.

39
Aquatic Biomes
  • Many aquatic biomes are stratified into zones or
    layers defined by light penetration, temperature,
    and depth.
  • The photic zone is the most productive.

40
Rocky Intertidal Zone
  • The rocky intertidal zone is alternately
    submerged and exposed by the tides.
  • Upper zones are exposed to air longer.
  • Physical stress (desiccation, waves, temp,
    salinity), predation, and competition produce
    distinct bands.

41
Rocky Subtidal Zone
  • Kelp forests dominated by brown seaweeds occupy
    shallow subtidal waters.
  • Grazing urchins and molluscs are common.
  • Predators include sea stars, fishes, and otters.

42
Rocky Subtidal Zone
CORAL REEFS
  • Coral reefs are limited to the photic zone in
    tropical marine environments with high water
    clarity.
  • Highly diverse

43
Nearshore Soft Sediments
  • Intertidal and subtidal environments with soft
    sediments include beaches, mudflats, salt
    marshes, sea-grass beds, and mangrove communities.

44
Nearshore Soft Sediments
  • Salt marsh habitat includes grasses, mussels,
    crabs, shrimp, and polychaetes.
  • Burrowing organisms.
  • Deposit or filter feeders.
  • Small fishes and birds that feed on them are
    common.

45
Nearshore Soft Sediments
  • Calm, tropical, coastal areas support mangrove
    communities.
  • Mangrove trees grow submerged in soft sediments.
  • Rich community of detritus feeders (oysters,
    crabs, shrimp).
  • Many fishes often used as a nursery ground.

46
Deep-Sea Sediments
  • The deep sea includes the continental slope,
    continental rise, and abyssal plain.
  • Sand where there are currents, fine mud where
    currents are weak.
  • Suspension feeding invertebrates are common.
  • Deposit feeders found in muddy areas.

47
Hydrothermal Vents
  • Hydrothermal vents occur on the abyssal plain in
    areas of submarine volcanic activity.
  • Archaebacteria that derive energy by oxidizing
    sulfides form the basis of the food chain.
  • Grazed by bivalves, limpets, and crabs.
  • Other organisms, like tube worms, have symbiotic
    archaebacteria.

48
Pelagic Realm
  • The pelagic realm includes the open ocean area.
  • High oxygen, low nutrient levels.
  • Areas of upwelling bring nutrients up from the
    sea floor.

OCEANIC PELAGIC BIOME
49
Pelagic Realm
  • Epipelagic surface waters
  • Mesopelagic twilight zone, supports a varied
    community of animals.
  • Deep sea forms depend on a rain of organic debris
    from above.

50
Zoogeography
  • Zoogeography describes patterns of animal
    distribution and species diversity.
  • Why species and species diversity are distributed
    as they are.

51
Zoogeography
  • The history of an animal species must be
    documented before we can understand why it lives
    where it does.
  • Camels originated in North America and spread to
    Eurasia, Africa, and South America.
  • Camels went extinct in North America 10,000 years
    ago.
  • Today, we see true camels in Eurasia Africa and
    camel descendents (llamas, alpacas etc) in South
    America.

52
Zoogeography
  • Geologic change is responsible for much of the
    alteration in animal distribution.

53
Zoogeography
  • Phylogenetic systematics allows us to reconstruct
    histories of animal distributions.
  • Geographical distributions of closely related
    species are mapped onto a cladogram to generate
    hypotheses of the geographic history.

54
Zoogeography
  • Disjunct distributions are closely related
    species that live in widely separated areas.
  • Dispersal a population moves to a new location.
  • Vicariance environmental changes break up a
    once continuous population into small pockets.

55
Distribution by Dispersal
  • Dispersal involves emigration from one region and
    immigration into another.
  • One way outward movement.
  • Different from a periodic movement back forth.
  • Active or passive
  • Center of origin
  • Explains movement of animal populations into
    favorable habitats adjacent to the place of
    origin.

56
Distribution by Vicariance
  • Areas once joined may become separated by
    barriers.
  • Population becomes fragmented into smaller,
    isolated populations.
  • Lava flows
  • Continental drift
  • Emergence of mountain ranges

57
Distribution by Vicariance
  • Vicariance by continental drift helps to explain
    the disjunct distribution of ratite birds.
  • Ancestral species widespread throughout Southern
    Hemisphere.

58
Distribution by Vicariance
  • As the continents moved apart, the ancestral
    species was fragmented into disjunct populations
    that evolved independently producing the
    diversity seen today.

59
Continental Drift
  • The concept of continental drift was proposed by
    Alfred Wegener in 1912.
  • Not fully accepted until the mechanism was found.

60
Continental Drift
  • Plate tectonics is the mechanism of continental
    drift.
  • The earths surface is composed of 6-10 rocky
    plates which shift position on a more malleable
    underlying layer.

61
Continental Drift
  • Pangaea the single great landmass broke up
    200 million years ago.
  • Two supercontinents resulted
  • Laurasia North America, Eurasia, Greenland
  • Gondwana South America, Africa, Madagascar,
    Arabia, India, Australia, New Guinea, Antarctica

62
Continental Drift
  • Continental drift explains several puzzling
    distributions of animals.
  • Similarity between some organisms in South
    America and Africa.

63
Continental Drift - The Case of Marsupial
Evolution
  • Marsupials appeared about 100 million years ago
    in South America.
  • They spread through Antarctica and Australia that
    were at that time joined together.

64
Continental Drift - The Case of Marsupial
Evolution
  • Marsupials encountered placental mammals in North
    America, could not compete, and became extinct.
  • The modern opossums are recent arrivals from
    South America.
  • The placental mammals expanded into South
    America, but the marsupials were well established
    there.
  • About 50 million years ago, Australia drifted
    apart from Antarctica and remained in isolation
    with only marsupials to diversify on the
    continent.

65
Wallaces Line
  • Wallaces line represents a geographic separation
    between Asian and Australian faunas.
  • A collision of tectonic plates brought formerly
    distant land masses closer together.

66
Temporary Land Bridges
  • Temporary land bridges have been important
    pathways for dispersal.
  • Land bridge connected Asia and North America
    across the Bering Strait.
  • Today, a land bridge connects North and South
    America

67
Climatic Cycles and Vicariance
  • Glacial cycles have occurred with durations of
    20,000 to 100,000 years within the past three
    million years.
  • Taxa sharing the same areas typically differ
    greatly in evolutionary age and in phylogenetic
    branching pattern.

68
Climatic Cycles and Vicariance
  • Cycling temperatures interact with the habitat
    requirements of animals.
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