Mass ExtinctionJacksury Puerta

Extinction is the process by which a species become extinct, no longer existing and living in the world.

Extinction is a normal part of evolution.Species come and go continually, around

99.9% of all those that have ever existed are now extinct.

Mass extinctions are events in which a very significant percentage of the species on the planet go extinct.

What is Extinction?

Ordovician-Silurian, 435 million years ago

Late Devonian, 370 million years ago

Permian, 250 million years ago

Triassic, 205 million years ago

Cretaceous-Tertiary, 65 million years ago

Five Mass Extinctions in the history of the planet Earth

Ordovician-Silurian Extinction

439 million years ago

Caused by a drop in sea level as glaciers formed, then by rising sea levels as glaciers melted.

Approximately 60% of marine genera were killed and 25% of marine families

Late Devonian Extinction• 364 million years ago• series of extinction over several million years•Caused by a asteroid impact and global cooling after the impact• Approximately 57% of the genera were killed and 22% of marine families•Life in the shallow sea were the most affected

Permian ExtinctionKnown as the “Great

Dying”, most severe extinction

96% of all marine species were killed

70% of land-living animal life were killed

Caused by change in climate and sea level when forces of the earth’s continents merge together.

Triassic Extinction• 2 or 3 phases of

extinction• 52% of marine

genera and 22% of marine families

• Caused by massive floods or lava erupting from central Atlantic province led by global warning

Cretaceous-Tertiary• Known as the K/T extinction• Famous for the death of the dinosaurs• 75% of all species became extinct•Happened at a rapid rate• Caused: by a volcanic event that produced the Deccan traps of India• An asteroid hit somewhere in the golf of Mexico in the Yucatan Peninsula

Known as the Holocene extinctionThis extinction event started at the end of the

last ice age, around 13,000 BP.Rapid pace - hundred years rather than thousand

years seen by the big five mass extinction.The rapid loss of species we are seeing today is

estimated to be between 1,000 and 10,000 times higher than the natural extinction rate.

E. O. Wilson estimates that 30,000 species per year (or three species per hour) are being driven to extinction.

Sixth Extinction

Sixth ExtinctionThe Extinction of nearly all forms of the large

mammals known as Megafauna, and the remaining species almost all threatened with extinction in the near future.

Unlike previous extinctions they were caused by climate change, the current crisis is caused by human activities.

Habitat destructionPollutionOverpopulationOver-harvesting (hunting, fishing, and gathering)Invasive speciesBy the year 2100, due to human activities half of

the world's marine and land species will go extinct.

What's causing this sixth extinction ?

 

This graph

shows the rise in

extinctions since

the human

population

The world’s leading scientists suggest that conservation measures, sustainable development, stabilization of the human population and the support of environmentally responsible economic development will be essential in halting the extinction crisis.

What can we do???

http://www.bbc.co.uk/nature/extinction_events

http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Holocene_extinction_event.html

http://www.rewilding.org/thesixthgreatextinction.htm

http://www.biologicaldiversity.org/programs/biodiversity/elements_of_biodiversity/extinction_crisis/

http://www.actionbioscience.org/newfrontiers/eldredge2.html

References