Evolving Thoughts

Evolution, culture, philosophy and chocolate! John Wilkins' continuing struggle to come to terms with impermanence... "Humanus sum, nihil humanum a me alienum puto" - Terence

Thursday, April 20, 2006

When is a species worth conserving?

It's not often one gets to see a dustup between taxonomists in the media. After all, taxonomy is such a civilised discipline, usually nobody gets killed and hospitalisation is rare. But here, in the Fort Wayne News Sentinel, is a piece on a match between Rob Roy Ramey, and Tim King, both field biologists, over the status of a mouse.

What's at issue is its status under the US Endangered Species Act, which focuses on conservation in terms of species rather than ecosystems, biodiversity, or viability of broader ecological systems. Ramey denied that a previously listed endangered species, Preble's meadow jumping mouse (that's some mouse, if it can jump entire meadows!) was in fact a species at all, but rather a subspecific population. King reanalysed the matter and decided that yes it was a species. And what is more, it was intimated, according to the article, that Ramey was "politically tainted" (which is code for, a Republican shill).

I'll get to the politics in a minute, but the taxonomic issues are of interest to me. The article talks about the "lumpers versus splitters" dispute in taxonomy, and wrongly attributes the recognition of this to Darwin (it predates him enormously, probably as long as naturalists have been describing species). A lumper blends variation into single taxa, while a splitter finely discriminates variants into their own taxa. There are lumpers and splitters at all levels of taxonomy, from superkingdoms down to subspecies, but the usual argy bargy is about species. Transitional forms have always been a problem. One anecdote about a student of Agassiz, Nathaniel Shale, tells of him stomping on transitional shells and exclaiming "That's the way to treat a damned transitional form!", in the late nineteenth century. One major problem of the nature of living things is that, well, they vary enormously and over gradients (morphoclines). Drawing the boundaries is tough, and sometimes a matter of convention.
Ramey disputes that the studies are really at odds. He says the differences come down to a question of how one interprets the data and where one chooses to draw lines between species. King draws them extremely finely; Ramey, less so. "What species concept you apply determines how you allocate your resources," Ramey told me. "We have so many things listed and too few resources to get the job done. We could go down the road of saying that every local population segment is a listable subspecies. But can we afford it, and will we be shortchanging arguably more important species? We can end up saving lots of little fish in each creek, and lose those creatures that are really unique."
And here is the problem. It's a matter of triage, due to limited economic resources. But focus on the "species concept" question. There is only one species concept - what is at issue here is the definitions and associated techniques and criteria for identifying a species. With the rise of DNA-based identification techniques, including the much-touted and much-criticised "DNA barcode", it is either the case that the genes used overgroup (lump) or undergroup (split) depending entirely on the evolutionary genetic history of the organisms. So the issue is really which serves the purposes best. In older days, species identification was based on phenotype, or in the older terminology, morphology - body shape, skeleton form, organs, and so on. This was convenient, but despite the mythology you'll find in some texts, it wasn't the whole story - naturalists before the modern period knew very well that there was variation of form, and that the identification keys were just conveniences. But some over-reliance on these techniques, hallowed by time and authority, led to bitter disputes. We see the same things happening today, only based on choices of molecular data rather than phenotype.

But what purposes are served by identifying species in conservation biology? It would seem that species is the focus because there is something objective about species, and so it validates the choices made for conserving biodiversity. If the diagnosis of species is assay-relative, that is, if it depends on what you use as the identification, the choice of assay is crucial. And that choice can be made to serve nonscientific purposes as well as scientific ones.

There is a movement, apparently successful (of which it seems Ramey is a part) to have the ESA rewritten. A movement known as the National Endangered Species Act Reform Coalition has successfully lobbied Congress to allow more political interference and economic considerations in the conservation process. The coalition includes such bodies as
  • American Farm Bureau Federation
  • American Forest & Paper Association
  • American Public Power Association
  • Colorado River Energy Distributors Association
  • Edison Electric Institute
  • Mid-West Electric Consumers Association
  • National Association of Counties
  • National Association of Home Builders
  • The National Grange
  • National Marine Manufacturers Association
  • National Rural Electric Cooperative Association
  • National Water Resources Association
  • Northwest Horticultural Council
  • Tri-State Generation and Transmission Association
all of which have vested interests in the outcome. If the Secretary of the Interior can overrule the Parks and Wildlife Service, based on whatever "scientific information" (the new wording of the revised act HR3824, the "Threatened and Endangered Species Recovery Act of 2005," which has passed the House of Representatives in the US, and is now before the Senate for ratification), economic interests will come to predominate.

Now this is not entirely a bad thing, for two reasons. First, it is entirely true as Ramey said that limited resources should be used to best conserve ecosystems, and second, that without the full support of the local communities and businesses, conservation is as doomed in the US as it is in the Congo. What worries me is that the tenor of the change indicates that this is not the motivation, but that this is a smokescreen for the undercutting of science that has been seen elsewhere by the present administration. All you have to do is change what is used to identify the species, and you can lump or split to serve political purposes.

Something like the Preble's mouse issue happened once before. The Red Wolf had been listed in 1967 as endangered under an earlier version of the ESA, but it turned out that as numbers declined, they hybridised with the more abundant coyote. A major debate followed, in which it transpired that there were no apparently unique alleles in the Red Wolf, and that it might not be a proper species. The Biological Species Concept was employed by those who argued that it was not a species, since it freely hybridised, so species concepts played a major role in that discussion too.

Part of the problem lies, I believe, in the focus on species. And that is a fundamental problem of the use of various, often arbitrarily chosen, measures of biodiversity. What really matters about biodiversity is the viability of entire ecosystems. At best, individual species are surrogates for that property. But nobody seems to be able to identify what that property really is. The problem is certainly with the ESA and equivalent legislation around the world, but the solution is hard to find. Some think there is no solution - biodiversity is just what we want to conserve in each particular instance. I think there is something worth pursuing here, and I have put in a grant application to follow it up. If it comes through, I'll certainly have more to say about this.

But it's nice to see my favourite species of biologists in the news. Taxonomy matters...