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 reset Life 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 CO 2 changes which can affect atmospheric and ocean chemistry (slow) an “oh shit” event

At least a dozen significant events

Five 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 diameter Impact 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 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 Toba Ice 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 Tuff was undoubtedly far more extensive.

Effect on Humankind (controversial theory) -Homo sapiens is remarkable for lack of genetic diversity in comparison to other primates  Something Happened “Bottleneck” scenario: Colossal near-species-extinction level event leaves small # of individuals Remaining (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 Recent Extinctions  Auroch (1627) & Dodo (1662)  Stellar’s Sea Cow (1768)  Mascarene Island Giant Tortoise (1795)  South African Cape Lion (1858)  Quagga (1883)  Passenger Pigeon (1914)  Tasmanian Wolf (1936)  Bali Tiger (1937) / Javan Tiger (1976)  Kaua’i ‘O’o (1987)  Golden Toad (1989)  Baiji White Dolphin (2006)  Chinese Paddlefish (2007)  Christmas Island Pipistrelle (2009)  Vietnamese Rhinoceros (2010)  Pinta Island Tortoise (2012)

By ?  50% of all species on the planet will be either endangered or extinct –Habitat destruction –Global Warming  25% mammalian species  15% bird species  In The Future of Life (2002), E.O. Wilson of Harvard calculated that, if the current rate of human disruption of the biosphere continues, one-half of Earth's higher lifeforms will be extinct by 2100 *we have operationally become GOD