Here’s a great idea for a super-power: what if by merely emitting a sound, you could detect nearby friends and enemies in the way the sound echoes? Echoes. Echoes.

For many species of bats and dolphins, echolocation isn’t a super-power but a necessity. It allows these animals to hear predators and prey without seeing them in the dark skies or cloudy oceans. This adaptation evolved separately in these mammals—a great example of convergent evolution.

Scientists at Queen Mary, University of London were curious how this type of convergent evolution looked at the genomic level. So they compared the complete genomes of 22 mammals, including new sequences of four bat species, to look at how echolocation is expressed in the genes.

To perform the analysis, the team had to sift through millions of “letters” of genetic code using a computer program developed to calculate the probability of convergent changes occurring by chance, so they could reliably identify “odd-man-out” genes.

Remarkably, they found genetic signatures consistent with convergence in nearly 200 different genomic regions! “We had expected to find identical changes in maybe a dozen or so genes but to see nearly 200 is incredible,” explains Queen Mary team member Joe Parker. “We know natural selection is a potent driver of gene sequence evolution, but identifying so many examples where it produces nearly identical results in the genetic sequences of totally unrelated animals is astonishing.”

Although many of the gene region similarities are in genes involved in hearing, which the team expected, others are all over the place, reports ScienceNOW:

…some genes with shared changes are important for vision, but most have functions that are unknown.

The team published their findings last week in Nature.

“These results could be the tip of the iceberg,” says group leader Stephen Rossiter. “As the genomes of more species are sequenced and studied, we may well see other striking cases of convergent adaptations being driven by identical genetic changes.”

So perhaps not a super-power, but a regular occurrence…

Image: Greg Hume

“Fa loves Pa.”

In Day of the Dolphin, George C. Scott teaches dolphins how to speak. They have names (Fa) and names for each other (Bea) and for their human companions (Pa). This cheesy 1973 Mike Nichols’ film is science fiction, but the movie did get two things right—dolphins do indeed have names for themselves and other dolphins in their pod.

Researchers in Scotland have been tracking dolphin name-calling (the nice kind, not the mean kind) over the past few years. Two previous studies determined that each dolphin has a signature whistle they use to introduce themselves to other dolphins, and that they can communicate with each other using these signature whistles. And the latest University of St. Andrews’ study demonstrates that dolphins respond to name-calling.

Stephanie King and Vincent Janik followed groups of wild dolphins and recorded the dolphins’ unique signature whistles. Think of the signature whistles as individual dolphin names. The scientists then took the recordings and altered them slightly with a computer, almost putting them in another “voice.” (NPR has a nice audio example of this.) When they played the altered recording back to the pod, the owner of that signature whistle (or name-holder) responded back with the same signature whistle, as if saying, “Yup, I’m here,” according to National Geographic. (Wired has an audio example of the call and response.)

Then the researchers delved deeper. They played back the signature whistle to the pod when that particular dolphin wasn’t there. The pod reacted, but without a response. The team then played back a signature whistle or name from a dolphin in a different pod. No reaction at all.

Showing that dolphins can be addressed in this way provided the missing link to demonstrate that signature whistles function as names.

“Our results present the first case of naming in mammals, providing a clear parallel between dolphin and human communication,” Janik says. “In experimental work, parrots are also good at learning novel sounds and using them to label objects. Some parrots may also use these skills in their own communication. Thus, both dolphins and parrots present interesting avenues of research for understanding labeling or naming in the animal kingdom.”

Their research is published this week in the Proceedings of the National Academy of Sciences.

Image: Serguei S. Dukachev/Wikipedia

Published today in PLoS ONE in an article called, “Thar She Blows! A Novel Method for DNA Collection from Cetacean Blow,” scientists reveal that they can collect DNA from dolphins, whales and porpoises by collecting the blow, or exhalations, from the animals.

Researchers at the National Aquarium in Baltimore collected blow and blood samples from six bottlenose dolphins between March and May 2010. A test tube was held inverted over the dolphin’s blowhole as they were trained to exhale on cue. Taken along with each blow sample, a control sample of seawater ensured that seawater did not contaminate any DNA results from blow samples. The blood collection occurred as part of routine medical examinations for the dolphins.

For all samples, blow and blood showed a perfect match for each individual animal. The scientists were therefore able to show that DNA can be successfully extracted from dolphin blow.

The researchers are now applying this less-invasive method of DNA collecting to animals in the wild. “Dart biopsying is considered inappropriate for very young animals and the technique requires considerable skill to avoid injuring the animals,” says Janet Mann, a senior author on the paper and a professor of biology and psychology at Georgetown University. “Thus identifying alternative genetic collection techniques for cetaceans remains a priority, especially for internationally protected species.”

Image: PLoS ONE

That’s what Stephanie Venn-Watson announced at the AAAS Meeting today.

Dr. Venn-Watson of the National Marine Mammal Foundation is the vet for a large group of naval dolphins here in San Diego. These dolphins “work” for the US Navy, detecting objects in the oceans—from missing persons to mines.

Several years ago, she was conducting routine blood tests on her subjects. As she compared the blood values of dolphins who fasted overnight to dolphins that were recently fed, she discovered something truly amazing. “Fasted dolphins had a series of changes in serum chemistries that matched those of people with diabetes. Interestingly, these same dolphins switched back to a non-diabetic profile after eating. There appears to be a switch that dolphins use to turn a diabetes-like state on and off.”

Diabetes seems to be a naturally healthy state for dolphins—probably as an adaptation to their diets. As big-brained mammals, they need sugar, but their diet consists entirely of fish—high in protein, but low in sugar. According to Dr. Venn-Watson, “The dolphins have found a way to use fish-protein diets to generate and control the glucose they need.”

Can this new understanding help people who have diabetes? It’s comparative genomics time! (To learn more about the Academy’s involvement in the comparative genomics field, click here.) Dr. Venn-Watson is hoping to take what she’s learned and apply it to humans. “Gene-based dolphin research could lead to a better understanding of how a fasting switch, which may be uncontrolled in some people with diabetes, can be controlled using the dolphin model. Its potential application to treat diabetes is enticing.”

Creative Commons image by Cayusa