Transcript Chapter 8 - Cobb Learning

Chapter 8
Biogeography
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.
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
Species Diversity
 Species
are not uniformly distributed over
Earth’s 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
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
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)
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
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
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
A
Provinces:
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.
6 Biogeographic Regions
 Nearctic
 Neotropical
 Palaearctic
 Ethiopian
 Oriental
 Australian
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
Known as “Wallace’s Realms”
Patterns in animals was the first step
The main biogeographic realms for animals are based on
genetic factors .
The major vegetation realms are also based on genetic factors
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
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
EXAMPLE:
Large Mammalian Herbivores
 Bison
 Capybara
 Kangaroo
 Giraffe
 All
N. America
S. America
Australia
S. Africa
in the same family
 All fill the same niche, in differing areas
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??
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.
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

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.
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.
Island Biogeography
 Theory
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
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
Why??
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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
 Adaptive
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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
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
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
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
3.
Temperate Dedicious 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
- 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