Ghost of a flea

The turtles and the volcano

Scientists infer a near-extinction event from lack of variability in the DNA of Island of Isabella turtles relative to other smaller islands in the Galapagos (via Fark). Conveniently, a local volcano is known to have erupted within the time-frame anticipated by analysis of genetic drift. Very clever that.

By studying the DNA found in the nuclei of the tortoise cells, the team was able to establish that the lack of variability was due to a contraction in the population some time in the distant past.

And by studying the DNA found outside the nuclei, in the cell's "power units" called mitochondria, the scientists were able to put a time to this contraction, or "bottleneck". This is possible because mitochondrial DNA changes regularly over time, allowing the emergence of patterns in its sequence to be clocked.

Posted by Ghost of a flea at October 4, 2003 08:34 AM