By ED YONG - NOT EXACTLY ROCKET SCIENCE
Added: Wed, 27 Jan 2010 00:00:00 UTC

Thanks to Thomas for the link.
http://scienceblogs.com/notrocketscience/2010/01/echolocation_in_bats_and_whales_based_on_same_changes_to_sam.php?utm_source=nytwidget


Millions of years before humans invented sonar, bats and toothed whales had mastered the biological version of the same trick - echolocation. By timing the echoes of their calls, one group effortlessly flies through the darkest of skies and the other swims through the murkiest of waters. It's amazing enough that two such different groups of mammals should have evolved the same trick but that similarity isn't just skin deep.

The echolocation abilities of bats and whales, though different in their details, rely on the same changes to the same gene - Prestin. These changes have produced such similar proteins that if you drew a family tree based on their amino acid sequences, bats and toothed whales would end up in the same tight-knit group, to the exclusion of other bats and whales that don't use sonar.

This is one of the most dramatic examples yet of 'convergent evolution', where different groups of living things have independently evolved similar behaviours or body parts in response to similar evolutionary pressures.

It is one of a growing number of studies have shown that convergence on the surface - like having venom, being intelligent or lacking enamel - is borne of deeper genetic resemblance. But this discovery is special in a deliciously ironic way. It was made by two groups of scientists, who independently arrived at the same result. The first authors even have virtually identical names. These are people who take convergence seriously!

Yang Liu from the East China Normal University had previously shown that echolocating bats share very similar versions of Prestin, even species that were only distantly related. This time, he sequenced the gene in even more bats as well as a wide range of whales. These included toothed species (dolphins, porpoises, orcas and sperm whales) that use sonar, and baleen species that don't.

Based on the DNA sequences of these Prestin versions, Liu drew a mammal family tree (a 'phylogeny'). It looked much like what you would expect, with the whales and bats clustering in separate family groups. But convert the sequences into amino acids and the picture changes dramatically. Suddenly, the family tree becomes utterly misleading. The echolocating mammals, be they bats or whales, are united as close relatives, to the exclusion of their rightful evolutionary kin.
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http://scienceblogs.com/notrocketscience/2010/01/echolocation_in_bats_and_whales_based_on_same_changes_to_sam.php?utm_source=nytwidget

TAGGED: BIOLOGY, EVOLUTION, GENETICS