extinction

Created by arioken 

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iridium anomaly

global spike in iridium concentration that indicated massive asteroid impact @ KT boundary

Tunguska event

1908 asteroid explosion over Siberia, heard around the world, just huge.

extinction

the death of a species - continuos ongoing consequence of env. change and nat. selection

Red Queen hypothesis

Species have a large amount of variation - but their genetic resources are finite
Environment never stops changing
Eventually even the most varied gene pool will be exhausted, species goes extinct [all species doomed]
Van Valen

gambler's ruin

With 50/50 odds, sometimes you win, sometimes you lose, but you WILL eventually bust.

random walk

random steps, never know where you'll be at any given point.

minimum viable population

the number of individuals below which a population cannot sustain itself.

species-area curve

shows that larger areas can sustain larger populations...loss of habitat=extinction

field of bullets

random survival

fair game

darwinian, survival of the fittest

wanton extinction

extensive extinction, not tied to adaptation (mass ext.)

background extinction

the regular extinction that constantly occurs bc of env. change and natural selection. 180-300 species every 1million yrs.

mass extinction

mass death of many species, abrupt change in earth's fossil record. eologically normal causes

regression (sea level)

fall of global sea levels (evident during great dying and KT boundary) effects reef environments.

kill curve

plots the probability of percentage of species killed in a mass extinction event over time
use a "kill curve" to predict:
1) Likelihood of major extinction events
2) Average waiting time between mass extinctions

big five extinctions

Probability of 5% or less on kill curve:
End Ordovician
Late Devonian
End Permian
End Triassic
End Cretaceous

shocked quartz

caused by impact event, shocked into distinctive, disorganized mineral array.

stishovite

octahedral shocked quartz, indication of impact shock

tektites

small glassy beads of liquified thrown off by massive impact event.

KT boundary

impact event likely caused extinction 65 million years ago, death of the dinosaurs. Also deccan traps messed stuff up w/ lava. Age of reptiles ends, age of mammals begin.

comet

are large cosmic snowballs, made up of frozen gases and dust
Solar wind blows a steady stream of gas and dust from the surface, creating a long tail

asteroid

solid balls of rocks, high metal content
Orbits take them throughout the solar system
Most are located in the asteroid belt, between Mars and Jupiter. May be the remains of a planet that did not coalesce when the solar system formed
Asteroids are 30 feet or larger (10 m),

meteoroid (meteor)

smaller objects are called meteoroids, asteroids smaller than 10m.

meteorite

meteoroids that survive earth's atmosphere.

periodic extinction

every 26 million years, impacts have high periodicity attributable to four causes:
1) Planet X
2) Nemesis
3) Vertical oscillations of solar system through the plane of the Milky Way
4) Passing through the spiral arms of the galaxy as the solar system orbits galactic core. All either unlikely or not compatable with data.

Oort cloud

Cloud of comets far out beyond the orbit of Pluto, at the outer edge of the solar system. Debris left over from the formation of Neptune and Uranus formed Kuiper Belt of comets, not sure if it exists.

Planet X

mysterious tenth planet, out beyond Pluto
Orbit so eccentric (highly elliptical) that it only swings in through the comet cloud every 26 million years.

Nemesis

sun has a distant solar companion. , has a very eccentric orbit
Swings back every 26 million years, disturbing the Oort Cloud

The Great Dying

Permian extinction event
Devastation was truly profound
Estimated 52% of all families, 90-95% of all species on Earth went extinct in a relatively short period of time
Extinctions affected big and small, aquatic or terrestrial

Siberian Traps

Massive volcanic eruptions that could have cause, or contributed too, the Permian extinction (Great Dying). Led to global nuclear winter, and possibly tons of acid rain.

continental drift

theory that continents drift around earth along lithosphere. Caused by convection currents in mantle.

Gondwanaland

formed by modern Africa, South America, Australia, and India. 200mya

Laurasia

formedby europe, asia, and north america. 200mya

Pleistocene blitzkrieg

Human caused extinction during the Pleistocene, ~10,000-15,000 years ago
72% of the Earth's large mammals disappeared

Common features of a mass extinction event:

Many species go extinct in a short period of time (30% or more)
Vanished species span all habitat types, sizes - marine and terrestrial, large and microscopic

eologically normal causes

Climate change
Sea level change (regression)
Extensive volcanism
Predation, diseases, parasites
Competition
Cosmic collision, rays

Characteristics that help survival

1) Being very widespread - greater chance that someone will be spared
2)High population densities - more numerous you are, higher chance some will make it through
3) Being lucky

Some species are much more vulnerable than others
1) Small population
2) Restricted range, habitat
3) Specialized niche

four ways in which smaller populations are vulnerable (simberoff)

Demographic randomness - random accidents can have a much greater effect on small popn.
Genetic deterioration - less variability, highly inbred, can't always adjust to rapid environmental change

evidence for large impacts

1) Big craters (duh)
2) Anomalous levels of iridium and other elements
3) Shocked quartz or other minerals
4) Mikrotektites in sediment
5) Soot particles

Possible causes of great dying

1) Possible asteroid/comet impact
2) Widespread volcanism
3) Global warming (methane release?)
4) Anaerobic conditions due to overturning of ocean sediments (releasing CO2)
5) Sea level changes (ice age?)
6) Breakup of Pangea (leading to global climate change)

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