What Is A Species?
June 8, 2008 12:12 AM   Subscribe

What Is A Species? "To this day, scientists struggle with that question. A better definition can influence which animals make the endangered list."
posted by homunculus (11 comments total) 3 users marked this as a favorite
A New Step In Evolution
posted by homunculus at 12:13 AM on June 8, 2008

Kind of morbid, that thought. "Your DNA test results are in. Mr. Fluffy, you are NOT endangered. Please step into the grinder."
posted by scope the lobe at 1:16 AM on June 8, 2008 [1 favorite]

Very interesting, but how much does it matter in the end? For example, I believe it has been established that neither the Himalayan nor the Sumatran tiger has any genes which don't occur in the Bengal tiger gene pool. So they can be seen as just shaggier and smoother subsets of the main tiger stock. But how much better does that really make you feel about them disappearing?
posted by Phanx at 2:41 AM on June 8, 2008

An interesting quandry of this nature is rainbow and steelhead trout (see also NPR story). They are the same species (to the point that two mating rainbow/steelheads can produce the opposite), but for some reason the steelheads behave totally differently and grow four times larger (going out to sea for years, while the rainbow stay in freshwater). As of a couple years ago, the steelhead were protected, while the rainbow aren't. I don't know what's become of the attempt to do away with the regulations since then.
posted by Dr.Enormous at 5:15 AM on June 8, 2008

Dr. E ...

Interesting point about the steelheads and rainbow. One important difference between the two, however: rainbows are farmed throughout the US, both privately and by various govt agencies. I don't recall seeing anyone successfully "farming" steelheads. One might go so far as to suggest that the steelheads are the "wild" rainbows...
posted by aldus_manutius at 5:58 AM on June 8, 2008

Steelheads can be farmed. And there are plenty of wild rainbows.
posted by event at 7:06 AM on June 8, 2008 [1 favorite]

Very interesting, but how much does it matter in the end?

It can matter a lot in conservation. For a population to be preserved, it has to be definable. Furthermore, a lot of conservation policy and legislation is phrased in terms of species. (Case in the question, the US, although the legislation ingeniously redefines a species as being a population.) This means that any conservation scheme can be filibustered by arguments over species boundaries.

Thus you end up with situations where an endangered species is discovered on a development or mining site. Conservationists call a halt to building or drilling. Developers say 'Ah, but there some argument over whether this is an actual species. Looks like there might be some horizontal gene transfer. This is not a species. Ergo: it's not endangered."

And there's a lot of cachet in identifying and naming species, which is why bird taxonomists keep splitting and lumping species into new identities. As the article states, species boundaries aren't easy, so this is going to go on forever ...
posted by outlier at 7:37 AM on June 8, 2008

"Species" are arbitrary divisions of nature applied by man, where the meaningful natural concept is the clade with the addition (read a nice thing about this, can't find it) that you really need a more general graph structure that sort of looks like a tree at first glance than a strict tree structure. It's pretty much the same thing as how people say "race is scientifically meaningless."

Darwin had it as quoted in the article:

“I look at the term ‘species’ as one arbitrarily given, for the sake of convenience, to a set of individuals closely resembling each other,”

posted by TheOnlyCoolTim at 9:44 AM on June 8, 2008

Interesting article!

Perhaps it is laws like the Endangered Species Act, which take for granted that we know what species are.

Not really true. Here's how it works under the ESA, in my non-lawyer understanding. It comes down to the definition of a Distinct Population Segment. And this is one of the things that gets lawsuits flying back and forth. There are two tests: discretence, and significance to its taxon. Take the orcas in the Puget Sound ("southern resident killer whales"). They frequently cross paths with transient killer whales, and with the northern residents. But they have their own vocal calls and greeting dances. Are they distinct? Is that difference significant? In June, 2002, NOAA said they were distinct, but that those particular pods were not significant; if they died, pods from the Northern Residents could come down and take up residence there. In 2003, "the judge was presented with a wealth of evidence that Southern residents are a unique and irreplaceable cultural community, which prompted the judge to instruct NOAA to review it all and reconsider their decision not to list the orcas under the ESA. NOAA did reconsider, and [in 2005] concluded that the Southern residents are indeed a cultural community, and needed protection under the ESA." Cool and interesting: from what I can tell, the fact that the southern residents are culturally unique is a large part of what made them qualify as a distinct population segment. Here's half of an interesting article about the whole thing.
posted by salvia at 6:23 PM on June 8, 2008 [2 favorites]

(By "discretence" I meant "discreteness.)
posted by salvia at 9:26 PM on June 8, 2008

Related thread.
posted by homunculus at 6:24 PM on June 10, 2008

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