To Web or Unweb…

Occasionally ironic juxtapositions of stories attracts GG’s interest, and today it is what to do about endangered species.

The idea that we as a society are capable of obliterating whole species and probably genera without even thinking about it has been around awhile. Recognition that this was in fact happening led to the enactment of the Endangered Species Act, a bill that had as a goal the preservation of species even if this was economically unpleasant. Given the massive impact humanity has had, from felling forests to drying rivers to polluting the air, it is impressive that only 10 of the around 1600 species ever listed have gone extinct, while more than 47 have been removed from the list as recovered and many protected species are recovering. By some measures, many more species have gone extinct before they could be added to the endangered species list.

This success has of course come at some cost. Ranchers have long decried protection of wolves, oil and gas drillers would like to wish away sage grouse, and many developers have been frustrated when their new subdivision would obliterate some population of animal. Critical habitat for endangered species covers more acreage than the national forest system. So it is not too surprising that some legislators, sensing opportunity in Washington, are hoping to restrict or even rescind this act.

The other dropped shoe is a more obscure scientific report that suggests that the megafauna extinction at the end of the Pleistocene has left a very tattered and fragile ecological web in North America, one where loss of a single species could tear large holes in that web. The paper itself seeks to use the historical experiment of the megafauna extinction to see how extinctions are related to changes in the functional diversity of ecosystems. In a sense the good news was that these older extinctions didn’t impact the functional diversity of ecosystems nearly as much as you might fear, especially once you allow for the impact of some introduced species, but the result was that many functional niches are only occupied by a few or even a single species.  Loss of such species would cascade through an ecosystem, putting at risk other species that took advantage of the opportunities that had been available. Thus the author finds “The largest functional richness losses may be yet to come because functional redundancy is low for many taxa including vulnerable species like the giant anteater (Myrmecophaga tridactyla) that now has no functional equivalent.”

This is, in a sense, the old John Muir quote “When we try to pick out anything by itself, we find it hitched to everything else in the Universe.”

You could argue that maybe we should prioritize saving species by determining how functionally unique they are–in essence, finding the keystone species and making sure they are doing well rather than trying to save everything. Maybe with perfect knowledge this would make sense, but there can be many ways a species might influence an ecosystem. Quite possibly you might let a species go only to find you missed a connection.

Given the frayed ecological web that emerged from the Pleistocene, it is prudent to be cautious in revising legislation that has succeeded in accomplishing its primary goal of preventing extinction. We shall see if such prudence emerges…

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