How many plant and animal species go extinct each year?
Some years ago Greenpeace claimed 50,000 -100,000 species each year.
In the comment thread of an earlier blog post Lamna nasus suggested a figure of 90 species of mammal over the past five centuries.
Professor Aynsley Kellow in his new book ‘Science and Public Policy – The Virtuous Corruption of Virtual Environmental Science’ describes the Greenpeace figure of 50,000 – 100,000 species as “virtual reality” made possible by mathematical modelling.
Professor Kellow links the Greenpeace claims, to the modelling of a so-called species-area relationship dependent on the idea that ecosystems are self-regulating and tend towards equilibrium.
Quotable quotes include:
“Ecology lacked a scientifically respectable method for studying life, and the ecosystem approach provided scientific respectability by supplying ecologists with mathematical tools developed by physicists.”
“An ecosystem is nothing more than a construction… Ecologists tried to study ponds as examples of ecosystems, but soon found even they were not closed systems but connected to the watertable, and affected by groundwater flows, spring run-off, migrating waterfowl…”
Professor Kellow goes on to explain the origin of the species-area equation and the theory of island biogeography as developed by Harvard biologist Edward O. Wilson. While the theory can explain the number of insect and arthropod species colonizing mangrove islands off the coast of Florida as a function of their distance from the mainland, the theory’s extrapolation to non-island situations and terrestrial ecology more generally is questionable. Furthermore predicting species loss by extrapolating backwards to suggest, for example, that a reduction in the area of forest will produce the same rate of species reduction as does its growth, has no basis in observational data but is common practice in conservation biology.
More quotable quotes include:
“In the absence of hypotheses which might be falsified by observational data, the extensive use of mathematical models introduces a virtual landscape where species, real and virtual, live and die, and where their utility to noble political causes restricts the scepticism of those who might question the validity of such ‘science’.
“Endangered species become not just trumps, but face cards in the game of politics used to create advantage.”
“The increased emphasis on mathematics which lent ecology its scientific gravitas helped steer it towards virtual science rather than experimental science, and it never shook off its normative shackles.”
“It perhaps became too abstract, a discipline attracting deskbound number crunchers more than those who liked to tramp about the woods in wool shirts counting deer scat.” [Kellow quoting Alton Chase]
“Wilson obviously finds beauty in nature, which is all very well, but to privilege this above other human needs as measured by opportunity cost is undoubtedly elitist and inherently anti-humanist.”
“There are, of course, all sorts of objections that can be raised against this virtual science. One fundamental problem is that it is based on the erroneous notion of ecosystem stability, since equilibrium lies at both the base of the theory and in the prescriptive concern with ecosystem maintenance.”
They say that extinction is forever, but in Australia “de-extinction” seems to be a regular occurrence. There have been very few mammalian extinctions, perhaps none, in Australia in the last 50 years (full species rather than sub-species), but in the same period there have been about a dozen species rediscovered, that had previously been considered extinct.
Chris Johnson says
Response to ‘braddies’ – the following Australian mammal species (all full species) have gone extinct since 1950:
crescent nailtail wallaby
As well, the following have gone extinct on the mainland in that time and survive only on islands, where they remain highly extinction-prone:
There have certainly not been a dozen species rediscovered. Gilberts potoroo, bridled nailtail wallaby, and mountain pygmy possum are in that category. All persist only in tiny numbers and are likely to go extinct any time.
There is no evidence at all that the pace of extinction in Australian mammals has slowed down. If anything, things are getting worse.
““Wilson obviously finds beauty in nature, which is all very well, but to privilege this above other human needs as measured by opportunity cost is undoubtedly elitist and inherently anti-humanist.”
Seems the prof is wont to engage in a bit of politics himself, and readily deployed by this blog I note.
Today I heard a promo for a new “Nature” program on public television (left-wing), and the show covers the concern that man will destroy a species that has been around for 350 million years. Yeah, right. The horseshoe crab made it for 350 million years, but it can’t survive humans. Some people, maybe like those in Greenpeace, would rather the human species go extinct.
Crash: A Tale of Two Species (32 second video)
“Survivor from the days of the dinosaur…. Can this ancient creature survive?”
Call me a skeptic.
Aynsley Kellow says
I don’t attempt to deal in any meaningful way with actual extinctions in my book, but, rather, with the virtual extinctions of mathematical modelling. I contrast this with the recorded observed number of species extinction in the past 500 years, which (according to the IUCN) is about 800.
My point is not to belittle the need for conservation. I think any species that can be saved should be – as long as the prospects for success are good and the price is not too high. Especially, I should add, in human terms, as I am an avowed humanist and therefore unapologetically ‘speciesist’. I just happen to think that the cause of conservation is advanced by generating fanciful numbers of virtual species that have become virtually extinct in a dubious computer model.
I also take issue with the harnessing of endangered species to NIMBY and numerous other campaigns. (I have, fancifully, posited Kellow’s Law, which states that sightings of endangered species will be clustered around the sites of development proposals).
I think conservation of Australian mammals is extremely important, but I think I side with Braddles rather than Chris on the point in dispute. Almost all the species Chris cites became extinct before 1950, and the Lesser Bilby probably did, being granted that status in the 1950s (about 1957, I think). But the causes of all of them lie before 1950: foxes, cats, farming practices.
Desert rat-kangaroo: last observed in 1935 (considered by the IUCN Red List to be the last reliable record of the species)
Pig-footed Bandicoot: last spotted in 1901.
Crescent nailtail wallaby: thought to have become extinct 1956, but in serious decline since early 20th C
Central hare-wallaby: last sighting 1940s
Desert bandicoot – last known specimen was collected in 1943
Lesser bilby: recorded as a living animal on just a handful occasions between its discovery in 1887 and its ‘official’ extinction in the 1950s.
Others might be able to come up with one since 1950, but it does seem that our record of conservation (saving and rediscovering)has not been too bad since we really started to care. There does not seem to be evidence that the rate of mammalian extinction is accelerating – though that does not mean many are are endangered, nor that we should not care.
Aynsley Kellow says
OOPs: I meant: ‘I just happen NOT to think that the cause of conservation is advanced by generating fanciful numbers of virtual species that have become virtually extinct in a dubious computer model.’
Chris Johnson says
all of the species on that list of recently extinct Australian mammals survived past 1950, as verified by interviews conducted with knowledgeable Aboriginal people across central Australia during the 1970s and 1980s. There was very little museum collecting done for any of them, which explains why last collection dates of specimens pre-date extinction by decades. All were widespread and common in the central and northwestern deserts until quite recently. This is published and reliable information.
Certainly, the declines began in the 19th and early 20th century, but they continued because the ecological pressures causing decline continued to operate or intensified through time. A new wave of mammal declines recently began across northern Australia, and I predict a further wave of declines and extinctions in Tasmania.
Our record of mammal conservation is woeful, and set to get significantly worse unless some serious re-thinking of the causes is done. If you want to know more, have a look at my book on the problem (Australia’s mammal extinctions, Cambridge Uni Press 2006)
Aynsley has a lot of sensible stuff to say about the probably insolvable issue of threats to various species. If the threat is defined by cuteness and visibility rather than value to the planet , we may not have a lot of hope, except that nature fills niches quickly. But given that big changes are possibly/probably happening from current trends in climate, how should that inform conservation policies? Go Aynsley. (tip Reds to do Highlanders).
Aynsley Kellow says
The many tasks on my desk requiring urgent attention before the annual influx of students will probably preclude me reading your book for some time, unfortunately.
I’d certainly be interested in hearing the gist of your argument, though. I don’t doubt that there are many mammals in danger, and I would certainly argue that we should focus on them rather than the distraction of the virtual species. (I would not wish to live in a world without tigers, orangutans, etc, but there are probably a few thousand slimes and molds I would not mourn too long for, even though I know that collectively they perform essential roles).
As you can see Bazza, I’m a sucker for the charismatic megafauna too! Not that I have anything against slimes and molds, but I think there’s a fair bit of redundancy there.
As for your reference to Reds and Highlanders, you’re touching on two of my past domiciles there, but I’m a Christchurch native and would probably incline towards the Crusaders when I watch the game where the ball is not seen for minutes on end. Perversely, I prefer the round ball and AFL and am now a short-suffering (formerly long-suffering) Geelong supporter, still wallowing in the afterglow, and strangely relaxed (at least until Round 1).
Prof Kellow what government agencies are making conservation policy on extinction rates based on virtual reality modelling of species-area relationships? Or is it just Greenpeace?
And OK Chris Johnson – I’ve just ordered your book. Is there any good evidence that land disturbance in recent decades in Australia – land clearing and/or pastoralism – has contributed to any decline in species diversity or extinctions ?
Or are feral animals the main issue?
chris johnson says
Land clearing etc has placed extra pressure on mammal species, but nether in recent nor earlier times does it seem to have been a primary driver of decline and extinction. For only one species is there a good case that extinction was primarily due to vegetation change (that’s the toolache wallaby, an especially beautiful macropod that went extinct in SA during the 1930’s).
Otherwise, the main cause was predation by cats and foxes (or by people on the thylacine). Vegetation change can increase exposure of vulnerable species to those predators, but removal of dingoes has probably been more significant. There is growing evidence that dingoes suppress cats and foxes, and thereby protect biodiversity. This explains, for example, why bilbies survive where dingoes are common but not where they are absent.
And Aynsley, I am a practicing ecologist and your criticisms of my discipline as being model-driven and lacking rigour don’t ring true to me. Ecologists are actually pretty good at challenging models with data and testing hypotheses, and this is as true of work on the species-area curve as anything else.
Aynsley Kellow says
It’s not a particularly Oz-centric book, but I do include details of the use of modelling in the Bald Hills Wind Farm case as an example of the embedding of values in models for particular effects – in this case to allow the former Coalition government to honour an election promise to block the development.
I was talking with my colleague, sociologist Adrian Franklin yesterday, and he tells me he has numerous interesting Australian examples of the uses and misuses of endangered species in his recent book ‘Animal nation: the true story of animals and Australia’ (Sydney : UNSW Press, 2006). I haven’t read it, but Adrian has a very strong international record on the sociology of nature/animals.
I don’t doubt that you ARE a check-shirt wearing scat gatherer, but there are many who are not, and as the observers and critics I quote in my book note, the discipline took a turn exemplified by Lord May: a physicist by training who rose to pre-eminence in ecology on the strength of his mathematics rather than his fieldwork. I know many scat-gatherers, too, and I have much respect for them.
> the show covers the concern that man will destroy a species that has been around for 350 million years. Yeah, right. The horseshoe crab made it for 350 million years, but it can’t survive humans.
Why would you think that they can? Does their survival for millenia suggest they are immune to pressure by humans as to NOT go extinct? The lungfish in Australia has been around for some 380 million years and researchers fear it will become extinct at the hands of humans. Such denial that humans can cause extinctions of creatures of various fossil record and genetic history is what can actually push these creatures into their coffins.