Week 10 - Biogeography II Flashcards
How does biogeography relate to geography?
Geography: Why what is where.
Biogeography: Where species are and why they are there.
What is endemism?
Being unique as a species within a certain geographical area.
What is the difference between being endemic and indigenous or native?
Indigenous or native species are found in a given area, but may also occur elsewhere.
What are some areas with high endemism?
Madagascar, Hawaii, New Caledonia, Lake Baikal, the Galapagos Islands.
What are five barriers that contribute to endemism?
Islands, mountain ranges, rivers, transition to desert, or another biome
What are some factors that limit what kind of species can be found on or around mountains?
Terrain, wind, life zones, etc.
What are some causes of species distribution?
Climates; soil; predators, prey, and symbionts; and other species that provide habitats.
Which soil factors can affect species distribution?
Minerals, moisture, precipitation, evaporation (controlled by wind and insolation), and erosion.
Which temperature factors can affect species distribution?
Extremes, averages, seasonality, duration, diurnal differences.
Where do plant species obtain nutrients from?
The soil.
What abiotic factors in regards to the soil may affect species distribution?
Abiotic factors such as pH, nitrogen and phosphorus content, soil grain size may limit range
What climate factors can affect species distribution?
Temperature, humidity, wind velocity, and sunlight.
How does wind velocity affect species distribution?
It affects evaporation, seed distribution, and the way plants grow.
What factor of sunlight is important in regards to species distribution?
Photoperiod, which is affected by latitude and altitude.
Which topography factors can affect species distribution?
Slope, altitude, and aspect (direction of slope).
What is a cosmopolitan species?
A species that occurs wherever that environment occurs.
Give examples of cosmopolitan species.
Humans, cats, krill, rats, blue whales.
Why are only a few species considered cosmopolitan?
Because most species only occur on one continent.
How does a species become cosmopolitan?
Two ways:
- Broad range of environmental tolerances
- Rapid dispersal compared to the time needed for evolution
What are the two main camps for why species occur where they do?
Environmental and historical
What are some historical reasons for species distribution?
continental drift, sea level changes, and glaciations
What is niche theory concerned with?
Environmental causes for species distribution.
What do we assume about “where they ain’t” in niche theory?
We assume that “where they ain’t” is a random distribution.
How does niche theory work?
It’s the process of using computer algorithms to predict the distribution of species in geographic space on the basis of a mathematical representation of their known distribution in environmental space (= realized ecological niche).
How does the WWF define an ecoregion?
A large unit of land or water containing a geographically distinct assemblage of species, natural communities, and environmental conditions
What is the definition of an ecoregion?
There is no simple, single way to define them.
What is the difference between a bioregion and a biome?
Although they are both continental, a bioregion is historical whereas a biome is environmental.
What is the difference between an ecoregion and an ecosystem?
An ecosystem is a small area whereas an ecoregion is a larger area–a region.
What is an ecotone?
A transition zone between two biomes; the borders of biomes are not sharply defined, and they tend to merge from one to the other; these areas of murky definition are called ecotones.
Most _______ are quite variable with _______ that are different from the _______ in which they’re located.
Most ecoregions are quite variable with ecosystems that are different from the biome in which they’re located.
In layman terms, how does niche theory work?
After determining what combination of environmental factors a species is likely to occur under, we can then plop that info onto a geographical space to try and determine where a species might occur.
What is an example of niche theory in practice?
New Zealand placing endangered birds on islands that are suitable, though not native to the birds; modelling fauna distribution under global climate change scenarios; modelling the geography of species invasion.
