pleistocene glaciation Flashcards
what determines terrestrial biomes
temperature and precipitation
patterns of biome distribution are along what gradient?
latitude
what determines aquatic biomes
water temp, salinity, depth (light and pressure)
spatial autocorrelation
“distance decay”
- distance increases = increase difference b/w environments
geographic gradients
patterns of variation
- elevation, temperature, latitude/longitude
geographic template
nonrandom patterns of spatial variation
- determines geographic patterns of populations, species, communities
ecosystem engineers
species that can modify their geographic template
solar radiation and latitude
- warms temp
- converted to chemical energy
- varies by location
3 mechanisms of heat transfer (higher to lower temp)
conduction, convection, radiation
conduction
direct heat transfer (solids)
convection
heat transfer through gas or liquid
radiation
waves pass through space
- sun –> earth
- heats matter depending on type
radiation is a function of ?
latitude
elevation
- cooling and decreased air as inc.
- decreased density of air above = cooler (less molecules) and thinning air
adiabatic cooling
expanding gases lose heat as molecules move apart
greenhouse effect
H2O vapor and CO2 absorb radiant heat
- inc. radiation = inc. reflection = dec. absorption
which side of continents is cooler?
wind-ward side (bc of rain shadow effect)
wind patterns at the equator
air heated –> expands –> less dense = rises –> reduced pressure = SURFACE WINDS
Coriolis effect
winds blow E –> W = slower bc they go against earth’s W –> E rotation
3 wind belts
polar easterlies, prevailing westerlies, tropical easterlies
westerlies
winds blowing toward poles deflected east
- important for trade (boat) routes
what drives major ocean currents?
surface winds and Coriolis effect
Mediterranean climate
dry/hot summers, mild/rainy winters
rain shadow effect
causes warm/dry climates on leeward side of temperate mountains
el nino year
no Humboldt current = increase in water temps and rain = warmer years
- ~4-7 years
la nina year
Humboldt current = brings cooler water from poles –> equator = cooler years
humboldt current
drives cooler water poles –> equator
enzo effects
el nino/la nina cycles; from current patterns
milankovitch cycles
cyclical changes in earth’s orbit around the sun
eccentricity
how E’s shape orbit ≠ perfect
- ellipses (not circle)
- effects heat budget and distribution
precession
orientation of earth’s axis on the solar system
- solstice = most s. radiation
what drives glacial periods?
milankovitch cycles
how many major ice ages?
5
first glacial period
huronian
cryogenian ice age
most intense
- “snowball earth”
- earth = completely frozen
Phanerozoic ice ages
3 glacial periods:
- andean/sahavan
- Karoo
- cenozoic
pleistocene glaciation
- ice = 1-2 miles thick
- glaciers melt
pleistocene epoch notable event
- epic ice age ends; glaciar melt –> great lakes
cycle of glaciation
~40,000-100,000 year cycle of glacial and interglacial periods
how many peak glacial periods?
~5 in last 400,000-500,000 years
how do milankovitch cycles drive glacial cycles?
- inc. eccentricity = inc. distance from sun = dec. temp
- inc. obliquity = dec. temp
precesion
amount of sun/earth tilt
inc. glaciation cause what feedback loop?
inc. snow/ice = inc. reflection of sun (inc. albedo) = dec. absorption of sun heat = drives continued glaciation
how do glacial fluctuations effect the planet in non-glaciated regions?
- dec. temp
- inc. snow at lower elevation
why was the Sahara desert huge during glaciation?
lack of water (in glaciers not in air) = inc. drieness
importance of the Pleistocene glaciation
- Pleistocene = last epoch (before current)
- important major glaciations
- created the great lakes
LGM (last glacial maximum) =
Wisconsin Glaciation
- 20,000 years ago
- melting = Great Lakes!
driftless area
small portion of Iowa, Wisconsin, Illinois w/o any historic glaciers
- glaciers always surround area (in each 5 glaciation periods)
- created rock formations and deep river valleys
formation of the great lakes
- glacial retreat after Pleistocene
- ice melts = largest freshwater body
the Great Lakes make up __ of all of earth’s freshwater
1/5
the land under the Great Lakes is still recoiling/rising from…
the Pleistocene glaciations; 1-2 miles of ice
beringia
land bridge b/w Asia and North America exposed during sea level fall
bering strait
land that connects asia/North America
what was important about beringia/bering strait?
allowed for exchange of life b/w previously isolated continents
- plant/animal migrations –> human migrations
epeiric sea/epicontinental sea
sea level rise/fall exposes or floods portions of continental plates
megafauna
very large animals (mostly mammals); previously dominated
- ex: mammoths
megafaunal extinctions
humans and climate = mass micro-extinction of megafauna
we are currently in a ___ period
interglacial
biological evolution
changes in heritable characteristics of a population over generations
4 important points of biological evolution
- heritable (descent w/ modification)
- random genetic changes (common ancestry and mutations)
- population level
- over time (generations)
natural selection is an example of…
a mechanism for biological evolution
5 types of biological evolution
- genetic drift (bottleneck and founder effects)
- sexual selection
- random mating
- horizontal gene transfer
- natural selection
genotypes
genetic changes: mutations
phenotypes
physical changes (appearance)
biological fitness
ability to reproduce and pass on genes to future generations
- new traits that increase survival = adaptations
5 components of natural selection (VISTA)
V: Variation by non-random mutations
I: Inheritable
S: Selection (environmental pressures)
T: Time
A: Adaptation (@ population level)
