Extinction: Co-Evolution, Niches, and the Opening of New Evolutionary Opportunities

1. Extinction: A large Scale Random Transformation

2. 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

3. New Evolutionary Niches Open The Rats Become the Kings

4. Implications: • 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”

5. Potential Triggers • Asteroid Impacts = sudden

6. Gradual: Large Basalt Outflows • Large CO2 changes which can affect atmospheric and ocean chemistry (slow) an “oh shit” event

7. At least a dozen significant events

8. Five Agreed Upon Major Events

9. Many events of varying extinction percentage amplitude The struggle Relatively stable

10. 65 Million years ago • 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).

11. Large Animals Perished • 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

12. 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.

13. (Probable) Climatic Effects of Toba Ice core samples from Antarctica and Greenland: Global circulation of ash from Mount Pinatubo, 1991 – atmospheric presence of Toba Tuff was undoubtedly far more extensive. • 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.

14. Effect on Humankind (controversial theory) 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. -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.

15. 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)

16. By 2050 - 2100? • 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