The Snail Darter is a Modern Day Myth

Snail Darter

At Althouse, "'There is, technically, no snail darter,' said Thomas Near, curator of ichthyology at the Yale Peabody Museum."

"Dr. Near, also a professor who leads a fish biology lab at Yale, and his colleagues report in the journal Current Biology that the snail darter, Percina tanasi, is neither a distinct species nor a subspecies. Rather, it is an eastern population of Percina uranidea, known also as the stargazing darter, which is not considered endangered. Dr. Near contends that early researchers 'squinted their eyes a bit' when describing the fish, because it represented a way to fight the Tennessee Valley Authority’s plan to build the Tellico Dam on the Little Tennessee River, about 20 miles southwest of Knoxville. 'I feel it was the first and probably the most famous example of what I would call the "conservation species concept," where people are going to decide a species should be distinct because it will have a downstream conservation implication,' Dr. Near said."

Stargazing Darter

From "This Tiny Fish’s Mistaken Identity Halted a Dam’s Construction/Scientists say the snail darter, whose endangered species status delayed the building of a dam in Tennessee in the 1970s, is a genetic match of a different fish" (NYT).

When else have scientists "squinted their eyes a bit" to see a way to achieve a result they desired? When have they not? Who can ever feel secure that we know whether the "snail darter" is something specific or just another stargazer?

Far be it from me to defend taxonomists, who earned my ire when I was in high school by renaming a host of my favorite African Cichlids, but officially the Snail Darter exists as a separate species because scientists, with some (from their point of view) altruistic  reason, went through the motions of identifying it as one with a paper. While a very useful concept, the species is an attempt to impose order on a continually shifting collection of organisms. Generally thought of a distinct if they are incapable of fertile interbreeding with another similar species, that is not the test that is normally done when declaring a new species, and in fact, many named species may fertilely interbreed. At some level, the distinction between closely related species that may or may not overlap in range, and may interbreed if they do is essentially arbitrary Somebody has to decide, and since Linnaeus is dead, it's left to individual scientists and the process of peer review (which as we know is far from perfect). 

The darters (a group of small fish in the perch family) are perfect choices if you want to stop a dam, or other project near water. Often confined to relatively small streams and river, evolutionary drift and different environments often drive small differences in the appearance, and niche of populations in different areas, while migration and rare flooding events allow enough genetic mixing in a few places keep the underlying genes of the organisms from diverging too much. Grab a few from the area you want to stop development in, get a friendly scientist to re-describe them as a new, rare species, (endangered by the mere fact that it allegedly exists only where you looked for it), and voila! the perfect excuse.