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Chapter 8
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Biogeography
Why Were Introductions of New Species
into Europe So Popular Long Ago?
• Biogeography:
– The large scale geographic pattern in the
distribution of species, and the causes and
history of this distribution
Wallace’s 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.
The main biogeographic realms for animals are based on
genetic factors. Why is this so?
The major vegetation realms are also based on genetic factors. Why
do you suppose this is the case?
Biomes
• A biome is a kind of ecosystem. Similar
environments provide similar opportunities
for life and similar constraints.
– Rainforest
– Grasslands
– Deserts
Here you can see
the relationship
between
precipitation and
latitude.
Convergent Evolution
• The process by which species evolve in
different places of times and, although
they have different genetic heritages,
develop similar external forms and
structures as a result of adaptation to
similar environments
• Ex: shapes of sharks
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
Geographic Patterns of Life within a Continent
Island Biogeography
• Theory of Island Biogeography
– Islands have fewer species than continents
– The smaller the island, the fewer the species
• 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.
• 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
Environmental stress and
biogeography.
Explain this diagram in terms of immigration,
population & extinction.
Earth’s 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, don’t do it.
17 Major Biomes
1. 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
3. Temperate Deciduous Forests
- occur in warmer climates that the boreal forest
4. Temperate Rainforest
- moderate temperatures, over 250 cm/year of rain
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.
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