1. Chapter 8
Biogeography

2. 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.

3. 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

4. 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

5. 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

6. 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)

7. 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

8. 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

9. Wallace’s Realms: Biotic Provinces
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.

10. 6 Biogeographic Regions
Nearctic
Neotropical
Palaearctic
Ethiopian
Oriental
Australian
Known as “Wallace’s Realms”
Patterns in animals was the first step

11. The main biogeographic realms for animals are based on genetic factors .

12. The major vegetation realms are also based on genetic factors

13. 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

14. 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

15. EXAMPLE: Large 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

16. 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??

17. 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.

18. Convergent Evolution Example:
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

19. 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.

20. 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.

24. 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

25. 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

28. Adaptive Radiation: Ecological Island:
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

29. 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.

32. 17 Major Biomes Tundras 2. Taiga or Boreal Forests
- 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

33. 9. Tropical Seasonal Forest and Savannas
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.

34. - Have phytoplankton and estuaries 13. Intertidal Areas
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