Tue 17 Jul 2007
We have an endangered species list identifying organisms that are about to wink out of existence like the dodo and the passenger pigeon. Some of these should are listed because they are emotionally important to humans – like the bald eagle and the koala bear. Some folks bemoan the protection of the snail darter and the northern spotted owl when it interferes with an economic activity.
These lists are of limited value because they include only the organisms we know exist. The organisms we know of represent only a tiny fraction of those in the world, and hence only a tiny few of those in danger of extinction, so putting a few on a list from those few we know might make us feel better, but it is really myopic.
There is a good case for preserving biodiversity in all ecologies, as each organism fills an important place in the system. Arguments are made that minor players in an area (such as low populations of a specific creature) are not important because they don’t seriously effect the balance of the ecology. On a day to day basis, these organisms seem insignificant – the proportion of the photosynthesis, grazing, predation, parasitism, etc. in the ecology is just not significant enough to make a difference.
Recent research in the Census of Marine Microbes, part of the project Census of Marine Life, done by Mitchell Sogin at the Marine Biological Laboratory at Woods Hole, shows that in each sample of the microscopic life from a submarine ecology station there are always a few dominant microbe species in each sample but thousands more species that are present, but rare. Each ecological sampling point or station has an entirely new suite of rare microbes.
The question that this poses is: Why are there so many rare species? One hypothesis is that these rare organisms provide a reservoir of biological alternatives for an ecology. Perhaps the prevailing conditions allow some organisms to flourish, while the others just barely hang in there – crowded out by the winners. When the conditions become unfavorable for the dominant species, by change in conditions such as specific predation or disease, there are a wealth of takers for their position, so the overall ecology can keep going.
When entire ecological systems are disrupted, by overharvesting, forest burning, clearcutting, polluting, poisoning, paving, draining, intensive agriculture, flooding or invasion of foreign species the ecological order disappears. This means that not only the specific species that are prevalent are lost, but the entire ecological system – those species that are “waiting in the wings” are lost as well. This loss of biodiversity is the critical loss, not the loss of a single species. After all, individual species face extinction and loss of habitat every day.
It seems to me that a much more useful goal would be to preserve ecologies – not individual species. When an environment is modified it disrupts of the prevalence of each of its species. What is critical is that a full analysis is made to determine to the best of our ability what these changes imply for the many species within the system. Many times it is possible to push an ecology pretty hard without substantial change. In other cases, some actions can cause an entire system to collapse.
Figuring out what is likely to happen in a given scenario and acting in a responsible fashion is much more important than counting the dead birds along the way.
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