Bats and dolphins are two of the most celebrated users of echolocation, employing high-frequency sounds to locate prey, find their way, or to communicate. Now a new set of findings in Current Biology show that not only do the two different kinds of mammals use the same method, they also evolved nearly the exact same molecular means for hearing at high frequencies.
That second part was a surprise, study author Stephen Rossiter says: “It’s common on a morphological scale but it’s assumed not to occur at a DNA level because there are so many different ways to arrive at the same solution” [BBC News]. That is, while it’s quite common for different species to separately evolve similar features—like the tusks of elephants and walruses—it’s quite unlikely that natural selection working in separate species would settle an essentially identical gene and protein for growing tusks, hearing high-frequency sounds, or anything else. Or so the thinking went.
The gene in question, and the protein it encodes, are both called prestin. It’s present in the short hairs of the inner ear, the researchers say. Prestin changes shape when exposed to high-frequency sound, and this in turn deforms the fine hair cells, setting off an electrical impulse to the brain. So the protein has the important jobs of detecting and selecting high-frequency sounds for amplification [New Scientist]. Prestin is common across mammals, although many different variants exist; mutations of the human version cause people to lose high-frequency hearing. But the prestin proteins that echolocating dolphins and bats evolved are almost identical, the study says. By contrast, bats that don’t use sonar don’t have that version of the protein, despite the fact that they’re much more closely related to their fellow bats than dolphins are.
For biologist David Pollock, who wasn’t involved in the study, this new could open a new window to understanding protein evolution. These findings, combined with a previously identified example of molecular convergence in snake and lizard mitochondrial genomes, suggest that molecular convergence may be more common than scientists realize — “it’s [just] not always easy to detect,” Pollock said [The Scientist].
Related Content:
80beats: Radar May Keep Bats Away From Wind Turbines’ Blades
80beats: Tiger Moths Jam Bats’ Sonar Like a Helicopter in Enemy Territory
The Loom: How to Be a Bat [with high-speed video]
DISCOVER: Killing Whales with Sound
DISCOVER: How To Weave a Dolphin-Friendly Net
Image: flickr / Ken Lund
January 26th, 2010 at 6:14 pm
wow is it me or would this be damn near impossible? i could understand similar genes in related organisms, but the last common ancestor of bats and dolphins wouldve been…the LCA of almost all mammals, so the gap is huge.
but then again, prestin can probably be made only one way, so maybe its not surprising at all; if u want to use echolocation, prestin may be the only way to do it. if thats the case then we should expect to see prestin in all echolocation using animals.
August 18th, 2011 at 5:04 pm
The subsequent time I read a weblog, I hope that it doesnt disappoint me as a lot as this one. I imply, I know it was my option to learn, but I actually thought youd have something attention-grabbing to say. All I hear is a bunch of whining about something that you can repair if you werent too busy in search of attention.