Extinction is Forever - Wed Aug 24, 2011

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Extinction is Forever - Wed Aug 24, 2011

Post by Lisbeth » Wed May 23, 2012 3:11 pm


The extinction of species is not normally considered an important element of neodarwinian theory, in contrast to the opposite phenomenon, speciation. This is surprising in view of the special importance Darwin attached to extinction, and because the number of species extinctions in the history of life is almost the same as the number of originations.

Present-day biodiversity is the result of a trivial surplus of originations, cumulated over millions of years. The past decade has seen a resurgence of interest in extinction, yet research on the topic is still at a reconnaissance level, and our present understanding of its role in evolution is weak.

Despite uncertainties, extinction probably contains three important elements.

(i) For geographically widespread species, extinction is likely only if the killing stress is one so rare as to be beyond the experience of the species, and thus outside the reach of natural selection.

(ii) The largest mass extinctions produce major restructuring of the biosphere wherein some successful groups are eliminated, allowing previously minor groups to expand and diversify.

(iii) Except for a few cases, there is little evidence that extinction is selective in the positive sense argued by Darwin. It has generally been impossible to predict, before the fact, which species will be victims of an extinction event.

Of all species that have existed on Earth, 99.9 percent are now extinct. Many of them perished in five cataclysmic events.

According to a recent poll, seven out of ten biologists think we are currently in the throes of a sixth mass extinction. Some say it could wipe out as many as 90 percent of all species living today. Other scientists dispute such dire projections. Scientists are also debating how one species, Homo sapiens, may be triggering a modern mass extinction.

A Bench Mark for what we Lose!
The IUCN Red List of Threatened Species™ is widely recognized as the most comprehensive, objective global approach for evaluating the conservation status of plant and animal species.

>From its small beginning, the IUCN Red List has grown in size and complexity and now plays an increasingly prominent role in guiding conservation activities of governments, NGOs and scientific institutions.

The introduction in 1994 of a scientifically rigorous approach to determine risks of extinction that is applicable to all species, has become a world standard.

In order to produce the IUCN Red List of Threatened Species™, the IUCN Species Programme working with the IUCN Survival Commission (SSC) and with members of IUCN draws on and mobilizes a network of scientists and partner organizations working in almost every country in the world, who collectively hold what is likely the most complete scientific knowledge base on the biology and conservation status of species.

The Threatened Species Programme (TSP) is primarily aimed at fulfilling the South African National Biodiversity Institute (SANB!) mandate to monitor and report on the conservation status of South Africa's indigenous plant and animal species.

The TSP coordinates the collection of information on species, particularly those that are not well known, such as reptiles, spiders and marine fishes, through projects involving volunteers from the public, as well as scientists, taxonomists and conservationists from partner institutions across the country.

The data collected through these projects is used to assess species' status according to the internationally accredited Red List Categories and Criteria developed by the International Union for Conservation of Nature (IUCN).

The question is "are we just catalogueing the species we lose?" or are we having a positive impact on man induced extinction? 99.9% of every species that has existed on Earth is extinct.

It would seem that extinction and speciation is a natural cycle that will continue regardless of what we do!

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