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  Can you imagine a world that contained no Siberian Tigers?  No cheetahs?  No Blue Whales?  What about the Golden Toad or some other more obscure amphibian?  Or insects?  Do you care about them as much?   In the future such creatures may be forever gone from this Earth...never to return.  Or, at best, they may be found only in preserves, or perhaps only their germ plasm may be frozen. Have you heard of the Tasmanian Tiger, the Golden Toad, the Rodriquez Tortoise all recently gone?  Should we care?  Why should we care?  What can we do about it even if we do care? Why is genetic diversity or biodiversity so important?

Some say, those who have studied such things, that we are living in a period of great extinctions...perhaps the greatest ever, greater than the Cretaceous/Tertiary extinction in which the great reptiles disappeared, greater even than the Permian extinction event in which over 90 percent of known groups vanished forever.

To what do we owe this unfortunate series of events?  Why is the genetic diversity of the world disappearing at an unprecedented rate?  Some say there is one major factor in these extinctions--man.

On one end of the extinction spectrum, we have one species simply evolving into another.  This is the "best" type of extinction since the species is not really lost, but simply changed; it's genes have just been modified.


However, there have been times of mass extinctions:


  1. mid Cambrian
  2. at the close of the Cambrian
  3. at the close of the  Ordovician
  4. near the end of the Devonian
  5. at the Permian-Triassic boundary
  6. at the Triassic-Jurassic boundary
  7. at the Cretaceous-Tertiary boundary
  8. And the so-called "Sixth Extinction" (if you don't count the Cambrian ones)--the one going on today which may be the greatest thus far.

Figure 1. Extinctions over the past 600 million years - mass extinctions show up as peaks superimposed on a general decline in extinctions (diagonal line). The mass extinction marked as 'Maastrichtian' was the death of the dinosaurs. Reference:
Sepkoski, JJ, Jr. 1994. Extinction and the fossil record. Geotimes March 15 - 17


Figure 2. Changes in Biodiversity in the past 540 years (Phanerozoic). See Wikipedia.


Figure 3. "This figure shows the genus extinction intensity, i.e. the fraction of genera that are present in each interval of time but do not exist in the following interval."

See Wikipedia

  E.O. Wilson estimated back in 1993 that about 30,000 per year were disappearing, or approximately 3 per hour.  It has gotten worse since.

 As the Alliance for Zero Extinction has put it so eloquently:

     "Extinction is a natural part of life on Earth, but compelling evidence shows us that human activities have accelerated global extinction rates 100 to 1,000 times over rates typical of preceding millennia. Habitat loss, commercial exploitation, disease, and introduction of exotic species have led to range reductions and increased extinction threat for an expanding proportion of the approximately 26,000 species of terrestrial vertebrates. The 320 vertebrates mentioned above already succumbed to these pressures. What will the 21st century hold for the many more species now clinging to the ledge above extinction's abyss? Rates of extinction are predicted to rise even faster in the coming years as human populations expand, and more habitat is converted, especially in the tropics and in areas of high species endemism. The spread of the agricultural frontier, the invasion of island biotas by foreign predators, herbivores, and pathogens will make this extinction spasm even greater. Unless we stem the tide, our descendents will inherit a biologically impoverished world, look back with regret, and wonder why didn't we act more quickly to save an endangered planet."

What can we do?

1.  Stop habitat destruction, especially in the tropical rainforests.  Set up protected areas and establish programs to reseed cut over areas.  Entire habitats need to be preserved not small plots.

2.  Establish agroforestry--especially in cut over rain forests, various desired species can be grown which will cut back on the indiscriminate cutting and destruction of rain forests.

3.  Establish programs to help indigenous peoples to protect and restore their lands (See Rainforest Action Network with its Protect-an-Acre program).  At the same time they can be encouraged to protect and help in the recuperation of their land.

4. Establishment gene banks--seeds and germ plasm, realizing this is a stop gap measure.

5. Encourage in every way national and international organizations to help do their part in species and habitat preservation.

6. VOTE for politicians that are dedicated to our biotic future!

7. NEVER buy products from endangered species!

8. Do NOT buy exotic pets from stores even those bred in captivity if wild stock must be added to keep them healthy.

9. Lead a conservative life.  Try to use as little of the earth's resources as possible. Buy from ecologically aware companies.













Web Links

Extinction A nice summary

  of the terms.


BBC Popular Site on Extinction


Wikipedia article


Extinction Event a Wikipedia article with graph


Permian Extinction Links


The Permo-Triassic Extinction

An interesting site



Cretaceous Extinction Links

Volcano Greenhouse Theory


"Sixth Extinction" Links

"Sixth Extinction?" Read the article by Niles Eldridge.


Leakey & Lewin Richard Leakey and Roger Lewin discuss this idea.


Concerned Societies

The Alliance for Zero Extinction


Why Be Concerned?

Costs of Extinction