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hubie [soylentnews.org] writes:

Death Valley [wikipedia.org] is the lowest, driest, and hottest region in North America. In the middle of this valley is a 22 x 3.5 meter fissure in the rock named Devil's Hole [youtube.com] that opens into a vast flooded cavern. In this dark, hot, and oxygen depleted water lives Cyprinodon diabolis, aka the pupfish. These particular fish have always been a mystery because they are a distinct species from the other pupfish in the region and it had been assumed they were deposited in Death Valley when the glaciers receded 10,000 years ago, but being so isolated they would not have expected to survive due to inbreeding. In a Proceedings of the Royal Society B paper (DOI: 10.1098/rspb.2015.2334) by Chris Martin of the University of North Carolina Chapel Hill, he found that these fish are actually newcomers [newscientist.com] and this is an excellent demonstration of rapid species adaption.

To understand the fish’s history, he and his colleagues sequenced DNA samples taken from C. diabolis that had died from natural causes, and compared the samples with archived DNA samples from other pupfish species that live in Death Valley.

Using mutation rates estimated from pupfish species elsewhere, the team calculated how long the Death Valley pupfish must have been isolated from one another.

The team found that all the pupfish of Death Valley descended from a common ancestor about 10,000 years ago, which fits with the postglacial drying of the valley.

But the Devil’s Hole pupfish are much younger, with an estimated origin of just 255 years ago – long after the last time the valley was fully flooded. Yet in that short time, the population has diverged enough to be considered a separate species.

Original Submission