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.”
Woody,
> 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.
Luke,
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.
Chris,
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.
Luke,
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.