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Posts Tagged ‘extinction’

The New York Times website has a slideshow of species recently lost to extinction, or currently hanging on by a thread. I’d recommend having a look, although it makes for very depressing reading.

There are continual arguments about why we should bother to save animals that are on the verge of extinction – or why we should care if a species does go extinct. My personal view, for what it’s worth, is that I find animals inherently beautiful (e.g. the golden toad) and/or interesting (who knew there was a snail that used to give birth to live baby snails [which is what ‘viviparous’ means]?!) and it is absolutely tragic that no one will see a golden toad alive ever again. From a more selfish, human-centric point of view, many animal and plant species could provide us with medical help (e.g. this amazing frog – now extinct). Finally, although extinctions have always happened naturally, the current rate at which species are disappearing is far higher than the usual background rate of extinction (I’ll look for some refs to back this up, but it is published data) – and, far too often, it is human-related effects, such as overhunting, deforestation, the building of dams, or the introduction of invasive species to an ecosystem, that is to blame for a species’ demise. Frankly, what right does any of us have to wipe out a complete species; what gives another species any less right to live on this planet than a human?

Further Information

Strange Behaviours: lost and gone forever
Action BioScience: the sixth extinction

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The IUCN (International Union for Conservation of Nature) compiles a ‘Red List’ where each species is described and their status classified – from Critically Endangered (50%+ probability of extinction within 10 years or 3 generations (whichever is longer)) through Endangered (20% probability of extinction within 20yrs or 5 generations) and Vulnerable (probability of extinction of 10% within 100yrs) to Near Threatened and Least Concern (Fig 1).  A paper by Hoffmann et al (2010) published in Science today has analysed this data on 25,780 species of the world’s vertebrates (all mammals, birds, amphibians, and cartilaginous fish (sharks and rays), and most reptiles and bony fish) and found that one-fifth of Earth’s vertebrates are Threatened and that this figure is increasing yearly.

Figure 1. Red List categories (from IUCN website)

This is sad, but not wholly unexpected news – after all, although extinctions have always happened in our planet’s history, the current levels are 100-1000 times above pre-human rates (Pimm et al 1995) and it’s well known that a vast number of species are in trouble. Fortunately it’s not all bad news as Hoffman’s study also demonstrates that conservation does work and, although current levels of conservation are not enough to overcome the significant threats to animals, there have been successes with species being downgraded in recent time due to the efforts to conserve them. Hoffmann mentions that the Humpback Whale Megaptera novaeangliae has moved from Vulnerable to Least Concern since the commercial whaling ban in 1955, and Butchart et al (2006) calculated that between 1994 and 2004 at least 16 bird species were saved from extinction by the conservation programmes implemented for them; so a turn-around of the extinction trend is possible with concerted effort, political will, and public support.

With Hoffmann concluding that, on average, 52 species move one category closer to extinction each year, the time for us all to take action is now.

References and Further Info

Butchart SHM et al 2006. How many bird extinctions have we prevented? Oryx 40: 266-278

Hoffmann M et al 2010. The impact of conservation on the status of the World’s vertebrates. Science – published online 26 Oct 2010 (doi 10.1126/science.1194442)

IUCN Red Data category specifications

Pimm SL et al 1995. The future of biodiversity. Science 269: 347-350

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