Biogeography

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Chapter 8

• Biogeography

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Niche

• Explains how so many species can coexist as the
  competitive-exclusion principle states that
• Two species that have exactly the same
  requirements CANNOT coexists in exactly the same
  habitat
• Species that require the same resources can
  coexist by utilizing those resources under
  different environmental conditions.
• Habitat complexity allows for this
• ie a habitat they has, for example, varying
  temps. or precip.

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Habitat vs. Niche

• WHERE a species lives, is its habitat, WHAT type
  of conditions a species lives under is its
  ecological niche (the sum of all of the rages of
  tolerance under which it can survive temp.,
  climate, food sources)
• If we want to conserve species, then we need to
  ensure all of the requirements of its niche are
  present

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Species Diversity

• Species are not uniformly distributed over
  Earths surface.
• Biogeography - the large scale pattern in the
  distribution of species
• Terrestrial species and ecosystems change
  depending on soil, topography, elevation, etc.
• Ecological Gradiant Change in the relative
  abundance of a species over an area or a distance
• Pg. 134 in text

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Factors the INCREASE Biodiversity

• Physically diverse habitat
• Moderate amounts of disturbance, ie fire
• Small variation in environmental conditions
  temp. precip
• A high diversity at one trophic level increases
  the diversity at another
• An environment highly modified by life, ie rich
  organic soil
• Middle stages of succession
• evolution

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Factors the DECREASE biodiversity

• Environmental stress
• Extreme environments
• Severe limitation in a supply of an essential
  resource
• Extreme amounts of disturbance
• Recent introduction of an exotic species (species
  from other area)
• Geographic isolation (a real or ecological island)

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Early ideas regarding biogeography

• 1749
• Linneaus 1st scientific botanist, father of
  taxonomy
• Questioned Why was there more variety in plant
  species in N. America and China and not Europe?
  They had similar climates ??
• Explained by the Theories of Biogeography

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Alfred Wallace

• 1876
• British Biologist
• Co-discoverer (w/ Darwin) Theory of Evolution
• Big idea -- World is divided into 6 geographical
  regions (realms), based on fundamental features
  of the animals found in those areas

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Wallaces Realms Biotic Provinces

• Realm
• Major biogeographic regions of Earth that are
  based upon fundamental features of the plants and
  animals found in those regions
• Taxa
• Categories that identify groups of living
  organisms based upon evolutionary relationships
  or similarity of characteristics (ex species,
  families, orders)
• Biotic Provinces
• A geographical region (realm) inhabited by a
  characteristic set of taxa, bounded by barriers
  that prevent the spread of those distinctive
  kinds of life to other regions.

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6 Biogeographic Regions

• Nearctic
• Neotropical
• Palaearctic
• Ethiopian
• Oriental
• Australian
• Known as Wallaces Realms
• Patterns in animals was the first step

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The main biogeographic realms for animals are
based on genetic factors .
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The major vegetation realms are also based on
genetic factors
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Relationship among living things

• All living things are classified into groups
  called
• Taxa
• Categories that identify groups of living
  organisms based upon evolutionary relationships
  or similarity of characteristics (ex species,
  families, orders)
• KPCOFGS

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Realms

• Certain families are dominant
• Animals of these families fill particular
  ecological niches
• Animals of different genetic stock fill the same
  niche in other realms

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EXAMPLELarge Mammalian Herbivores

• Bison N. America
• Capybara S. America
• Kangaroo Australia
• Giraffe S. Africa
• All in the same family
• All fill the same niche, in differing areas

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Biotic Provinces

• Realms are now referred to as Biotic Provinces
• A region inhabited by organisms with the same
  taxa (sp. , fam. Order)
• Organisms share common genetic heritage
• Provinces are bounded by barriers that prevent
  spread to different regions and immigration from
  foreign species.
• HOW IS THIS EXPLAINED??

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Continental Drift

• All due to continental drift
• Wallace did not know this at the time
• The unification of the continents (Pangea)
  allowed for genetic mixing. Enabled organisms to
  enter new habitats.
• Separation, imposed genetic isolation and the
  evolution of new species.

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Convergent Evolution

• Given sufficient time and similar climates in
  different areas, species similar in shape and
  form will tend to occur.
• Example
• Joshua Tree
• Saguaro Cactus
• Euphorbia
• All tall with green succulent stems that replace
  leaves. Not closely related different families.
• Evolution under similar desert climates
  convergent evolution

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• Divergent Evolution
• Organisms with the same ancestral genetic
  heritage migrate to different habitats and evolve
  into species with different external forms and
  structures, but continue to use the same type of
  habitats
• Ex) Ostrich (Africa), emu (Australia) and rhea
  (s. America) - all evolved separately, but
  retain some common characteristics.
• Population divided, usually by geographic
  barrier.
• In open grasslands, a lg. bird that can run
  quickly, feed on small seeds and insects had
  advantages over other organisms seeking the same
  food.

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Biomes

• Biogeographic pattern
• Kind of ecosystem
• Similar environments provide similar
  opportunities for life and similar constraints
• Lead to evolution of organisms similar in form
  and function.

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Island Biogeography

• Theory of Island Biogeography
• Islands have fewer species than continents
• The smaller the island, the fewer the species
• New species on an island are a result of
  migration and/or evolution
• The farther the island is from the mainland, the
  fewer the species

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Why??

• Fewer habitats
• Some habitats are too small to support a
  population large enough to survive
• Small populations are easily extinguished
  flood, fire
• Smaller the population, the greater the risk of
  extinction
• Farther an island is from mainland, the harder it
  will be for an organism to travel the distance
• A small island is a small target less likely
  to be found
• Islands tend to maintain a constant of species

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• Adaptive Radiation
• The process that occurs when a species enters a
  new habitat that has unoccupied niches and
  evolves into a group of new species, each adapted
  to one of these niches.
• Finches on the Hawaiian Islands 16 species,
  each with specialized beaks for its food.
• Ecological Island
• An area that is biologically isolated so that a
  species occurring within the area rarely mixes
  with any other population of the same species
• Ex. ponds, city park, small stand of trees in a
  field

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Earths Biomes

• The Earth has 17 major biomes , each with its own
  characteristic dominant shapes and forms of life.
• Most biomes have been heavily altered by human
  action.
• People have introduced exotic species to new
  habitats sometimes creating benefits, often
  creating problems
• Primary Rule Unless there is a clear and good
  reason to introduce an exotic species into a new
  habitat, dont do it.

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17 Major Biomes

• Tundras
• - treeless plains that occur in the harsh
  climates of low rainfall and low average
  temperature
• - two types artic tundra and alpine tundra
• - parts have permafrost permanently frozen
  ground
• 2. Taiga or Boreal Forests
• - includes the forests of the cold climates of
  high latitudes and high altitudes
• - dominant life forms including moose and other
  large mammals, small flowering plants and trees
• Temperate Dedicious Forests
• - occur in warmer climates that the boreal
  forest
• 4. Temperate Rainforest
• - moderate temperatures, over 250 cm/year of
  rain

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• 5. Temperate Woodlands
• - Slightly drier climate that the deciduous
  forests
• - fire is common and species adapt to it
• 6. Temperate Shrublands
• - also called chaparral miniature woodlands
• 7. Temperate Grasslands
• - include many North American parries
• 8. Tropical Rain Forests
• - high average temperature and rainfall
• 9. Tropical Seasonal Forest and Savannas
• - high average temperature, low latitudes,
  abundant but seasonal rainfall
• 10. Deserts
• - The driest region that vegetation can survive.

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11. Wetlands - Include freshwater swaps,
,marshes and bogs all have standing water 12.
Freshwaters - Have phytoplankton and
estuaries 13. Intertidal Areas - Areas exposed
to alternately to air during low tide and high
tide 14. Open Ocean - Also called the pelagic
region 15. Bethos - Bottom portion of the
ocean 16. Upwellings - Upward flows of ocean
water 17. Hydrothermal Vents - Occur in the
deep ocean were plate tectonic processes create
vents