Here is a worthwhile short essay on biodiversity and the role of social norms in science. I particularly liked these paragraphs:
To begin with, it is apparent that "biodiversity" is not a factual observation, but a cultural construction. One way to construct it is by considering only biodiversity that arises from evolutionary processes, in which case loss of "traditional" species equates to loss of biodiversity. Alternatively, one can consider only designed biodiversity, in which case gains in constructed forms of life, such as GMOs or engineered bacteria constitute gains in biodiversity. Or one could consider overall information content of biological systems of all sorts as biodiversity, in which case no one knows whether it's increasing or decreasing.
What community gets rights to define the cultural construct of biodiversity matters because the definition of the term in large part bounds public perceptions, and thus potential policy responses. Biodiversity traditionally has been defined by the conservation biology community, which by self-selection, focus and training has a strong incentive to perceive losses in evolutionary biodiversity, and little experience or interest in understanding designed biodiversity at all, except perhaps as it overlaps "natural" systems (a major reason for this is that designed biodiversity tends to be found in industrial and agricultural systems, as opposed to "natural" environments). This definition accordingly is based on the construct of "species" generated by evolved biology, and - given the continued development of the anthropogenic Earth - necessarily implies a "crisis" in biodiversity, requiring in turn strong policy measures to "preserve biodiversity".
I might cavil at the claim that biodiversity is entirely constructed - after all there are empirical and theoretical quantities involved in most biodiversity measures. But it's a salutory piece worth reading.
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We can calculate some numbers, but so what? Most diversity indices are arbitrary biologically (e.g. Shannon's index): they have no links to the mechanisms. Species richness looks better, except that it's impossible to know if the estimate is any good.
I think the basic problem is that we can't find an operational definition of biodiversity, so there is no way of finding the right metric. It all ends up being a bit like porn: we can't define it, but we know it when we see it.
Bob
I do not buy his argument, not even a little bit. It looks to me like he's trying to take a basic (if inexact) concept from science and do the post-modernist thing with it:
Translation: Since we can't define it exactly, and consistently enough, to keep him from playing different scientists against each other, he's claiming it as a 'cultural construction' that gets defined by "whoever's in charge". To which I call "Bullshit".
OK, let's consider it. Every bioengineered form I've ever heard of -- heck, most domesticated forms -- has a serious "founder effect" bottleneck. In fact, their diversity in general sucks big-time, precisely because they've been tightly selected for our purposes. This is why we've had a steady stream of minor crises around the world, as various agricultural monocultures run afoul of the particular strains of blight or parasite that they aren't resistant to. This hardly seems proper cause to conjecture about "a cusp as the source of biodiversity shifts from natural evolution to human design", much less to to make a claim such as:
Oooh, lookit the scare quotes! :-) So, we just redefine the idea of biodiversity to include every trademark in the gardener's catalog, and presto, no more crisis? I don't think so!
David, I think that you are right on this matter. I failed to note that the author was employed by AT&T: it is possible there is an agenda here. But there's a deeper issue - it is true in my opinion that biodiversity measures are constructed. I have no doubt there is a biodiversity crisis, but at a recent conference of ecologists and conservation managers I attended, each measure of the crisis was unique, and the "measures" here were constructed for each case. Does this represent a problem in the disciplines, or a problem in the social implementation of conservation management? I don't, yet, have a view. The measures are defined by those in charge (usually state instrumentalities). The real issue is, should they be?
I agree with Bob - we know it when we see it. But surely a scientific approach ought to have something rather better than "this seems to work in this particular case"? Although it seems that no approach actually works, so far. Shannon indices are measures of the diversity in what we choose it measure. They can be applied to taxonomic diversity, genetic diversity, or trophic diversity equally. So the issue is what should we measure the diversity of, and why?
Neither. Bluntly, this has nothing to do with "social constructions". The basic problem is that we are trying to interpret the condition of extremely complicated systems, and it's not so easy to boil that down to some magical statistic. As that author might have wanted, "Just do whatever it takes to increase this number, and you're golden!" (Of course, he's also angling to pick the number!) Sorry, that's not how the real world works.
There are complicating factors as well: It's exactly the richest ecosystems that we don't fully understand -- not that we completely understand any ecosystem! Remember, we still haven't managed to create an artificial biosphere lasting more than a few weeks! We really don't know what the important factors are, or what should go into a "diversity index". Bears and trees, sure. Grass, flowers, mice... obviously important, but it's a bit harder to count them. Insects etc, worms, fungi... are your grad students getting bored yet? How about nematodes, mites, bacteria? Oh yeah, and it's not enough to catalogue all this stuff, you need to know how it fits together! A plant that was perfectly well-behaved back where it came from can turn into a crazed invader, without the parasites and other constraints of its former home....
There's also the issue that lots of the stake-holders just want to make the problem "go away", by any means necessary. I've heard there's a rule in economics, that as soon as you use an index for public-policy purposes, you start destroying the information that statistic used to give you. There's certainly something like that in conservation science, mediated by short-term responses to whatever index you emphasize. "Oh, you're worried about the water quality? No problem, we'll send the waste to an incinerator instead." Or worse: "Thanks to the past 10 years of protection, the garrulous roughbeak has replenished it's numbers! Now we can take it off the endangered species list, and... since that forest is no longer the habitat of an endangered species, let's turn it into housing developments!"
Because of this sort of feedback behavior, it's never enough to just draw numeric "lines in the sand" -- conservation intrinsically requires advocacy, because the issues really are about "values" both personal and economic. The argument of that original article really boils down to saying that these basic goals, of conservation and ecological stewardship, are nothing more than a passing fad among the intellectual classes. But to make that stick, you need to actively discredit the idea that they might be connected to anything more fundamental, or more important, than social theory. And that's where this guy gets his soapbox....
Don't you mean "salutAry"?
Oh, crap. Sorry. Didn't realize how dead this one was. My bad, henceforth will think before I type.