Extinction: A large Scale Random Transformation. CO-EVOLUTION & NICHES Any species living in a...

Extinction: A large Scale Random Transformation

CO-EVOLUTION & NICHES

• Any species living in a niche has evolutionary relationships with other species; some casual, some crucial

• Therefore, the extinction of a species will have repercussions in the niches of all species which have co-evolutionary relationships with the newly extinct species

New Evolutionary Niches Open The Rats Become the Kings

Evolutionary Clock gets periodically resetLife recovers (relatively rapidly) to fill new

ecological niches this empowers species diversification

This means that “survival of the fittest” doesn’t work on long timescales random catastrophe is MORE important

Strangely, nature confirms that a “new world will arrive out of the ashes of the old one”

Asteroid Impacts = sudden

Large CO2 changes which can affect atmospheric and ocean chemistry (slow)an “oh shit”

event

At least a dozen significant eventsAt least a dozen significant events

Five Agreed Upon Major EventsFive Agreed Upon Major Events

Many events of varying extinction percentage amplitude

Relatively stable

The struggle

KT extinction (dead dinosaurs) triggered by asteroid impact.

A 10km diameter asteroid, leaving a crater ~200 Km in diameterImpact caused acid rain, ash (from global forest fire) that directly blocked out the sun for months, severe global cooling (nuclear winter).

Before the end of the Cretaceous, flight evolved independently three times:Insects, flying reptiles, birds (avian dinosaurs)

By the end of the Cretaceous 65 Mya, most dinosaurs along with other large marine reptiles and various invertebrates died out

No land vertebrate larger than a large dog survived the KT boundary event

Toba catastrophe 74000 BC:The most recent supervolcano.

Proximity to equator

ability to affect all latitudes of globe, and for tephra circulation to be affected by trade winds.

Here is Toba,at 2 degrees north

of the equator.

(Probable) Climatic Effects of TobaIce core samples from Antarctica and Greenland:

-6-year period of sulphur deposition far above normal levels – sulphur and volcanic ash remained in atmosphere, blocking out substantial amounts of sunlight. – Nuclear Winter for 6—10 years.

Global circulation of ash from Mount Pinatubo, 1991 –

atmospheric presence of Toba Tuffwas undoubtedly far more extensive.

Effect on Humankind(controversial theory)

-Homo sapiens is remarkable for lack of genetic diversity incomparison to other primates Something Happened

“Bottleneck” scenario:Colossal near-species-extinction level event leaves small # of individualsRemaining (est: 5-10,000 breeding pairs of Homo Sapiens), who become the genetic root of the species.

Out of Africa Migration time line would place humans in proximity to the worst effects of Toba. Record shows that, 70,000 years ago, Homo Sapiens were the only surviving humanoid.

Recent Extinctions Auroch (1627) & Dodo (1662)Auroch (1627) & Dodo (1662) Stellar’s Sea Cow (1768)Stellar’s Sea Cow (1768) Mascarene Island Giant Tortoise Mascarene Island Giant Tortoise

(1795)(1795) South African Cape Lion (1858)South African Cape Lion (1858) Quagga (1883) Quagga (1883) Passenger Pigeon (1914)Passenger Pigeon (1914) Tasmanian Wolf (1936)Tasmanian Wolf (1936) Bali Tiger (1937) / Javan Tiger Bali Tiger (1937) / Javan Tiger

(1976)(1976) Kaua’i ‘O’o (1987)Kaua’i ‘O’o (1987) Golden Toad (1989)Golden Toad (1989) Baiji White Dolphin (2006)Baiji White Dolphin (2006) Chinese Paddlefish (2007)Chinese Paddlefish (2007) Christmas Island Pipistrelle (2009)Christmas Island Pipistrelle (2009) Vietnamese Rhinoceros (2010)Vietnamese Rhinoceros (2010) Pinta Island Tortoise (2012)Pinta Island Tortoise (2012)

By 2050 - 2100?By 2050 - 2100? 50% of all species on the planet will be either 50% of all species on the planet will be either

endangered or extinctendangered or extinct– Habitat destructionHabitat destruction– Global WarmingGlobal Warming

25% mammalian species25% mammalian species 15% bird species15% bird species In In The Future of LifeThe Future of Life (2002), E.O. Wilson of Harvard (2002), E.O. Wilson of Harvard

calculated that, if the current rate of human disruption calculated that, if the current rate of human disruption of the biosphere continues, one-half of Earth's higher of the biosphere continues, one-half of Earth's higher lifeforms will be extinct by 2100 lifeforms will be extinct by 2100 *we have *we have operationally become GODoperationally become GOD