Ch 52 - Physical Environment & Biogeography

1. Speciation rate is higher than extinction rate in the tropics

larger geographic area (largest diameter)
Warm and stable climate

2. Tropics had more evolutionary time to diversify

No ice ages like in temperate latitudes (increases accumulation of species)
More accumulation of species over time

3. Higher productivity in tropics

More resources and less competition: lower extinction rates

____ a natural process now altered by human activity

Greenhouse effect

_____ is the factor responsible for global climate patterns

Solar radiation

albedo

% of light reflected by any surface

Climate

Long term expectation of area's weather

Coriolis effect

Air and water deflect at different latitudes due to planet rotation

Deforestation leads to 

higher temperature and lower precipitation

Distribution of species is determined by ____

evolutionary history

Ecological systems are _____

hierarchical

Global biodiversity peaks at ____ 

tropics

Global precipitation is maximum at ____

equator

habitat fragmentation

habitats broken into smaller pieces due to human interference (deforestation, agriculture, urbanization)

Hadley cells

Atmospheric circulation and precipitation (0^o-30^o)

Heat islands

pockets of warm air created by cities

Hypotheses that explain high diversity toward tropics

1. Speciation rate is higher than extinction rate in tropics
2. Tropics had more evolutionary time to diversify
3. Higher productivity in the tropics

In the northern hemisphere, wind blows ______

clockwise

In the southern hemisphere, wind blows ______

counterclockwise

Incoming solar radiation disperses into

20% absorbed by atmosphere
50% absorbed by surface
30% reflected (by clouds/atmospheric gas & surface)

The atmosphere absorbs ___ of solar radiation

20%

Earth’s surface absorbs ___ of solar radiation

50%

Clouds/atmospheric gas & surface reflects ___ of solar radiation

30%

increasing # of species

small far, small near, large far, large near

Large + close to mainland =

more species

Ocean currents redistribute ____

heat in the planet

Ocean gyres and surface currents

spinning motion of ocean created by prevailing winds

Patterns of biomes where plants may be similar due to global patterns of temperature and precipitation

Terrestrial biomes

Physical environment is determined by ____, not weather

climate

Prevailing winds created by

deflected air circulation and rotation

Rain shadow phenomenon is due to ____

mountain ranges being close to oceans.
Mountain causes dry side on lee-ward side (sheltered from prevailing winds)

smaller islands have less diversity

due to higher extinction rates (less resources, more competition)

Species diversity increases with 

area (island) and proximity to source of species (mainland)

Subtropical deserts are formed around 

30N and 30S

The amount of solar radiation received changes during the year, resulting in _____

seasons

The amount of solar radiation received changes with ____

latitude (E/W)

Theory of island biogeography

diversity in an island reflects balance between rates of colonization and extinction

Upwelling zones

deep, nutrient rich ocean water rises to surface 

Vicariance

Separation via physical barrier

Weather

What happens in the immediate future/present

Where organisms can live is determined by ______

physical environment

Angle closer to poles

Spread over larger area

More absorption by atmosphere

Less radiation reaches surface = colder

Angle closer to equator

Spread over less area

Less absorption by atmostphere

More radiation reaches surface = hotter

Laurasia

North pangaea split

Gondwana

South pangaea split

Biogeographic regions

• Nearctic

• Neo-tropical

• Ethiopian

• Palearctic

• Oriental

• Australasian

• Antarctic