In a groundbreaking, new discovery, researchers have demonstrated that similar genetic traits can take very similar evolutionary paths in two totally different species. Their investigation focused on the genes that allowed both bats and dolphins to echolocate. In spite of the fact that they are worlds apart, inhabiting completely different ecosystems, the creatures exhibit the same variations over time in the same group of genes, with the same end-result – the ability to detect very high-pitched sounds, and therefore to use echolocation, the BBC News reports.
This ability allows blind creatures such as bats, or animals living in the oceans, like dolphins, to communicate with members of their own species almost instantly. In the case of the flying creatures, echolocation also replaces sight. The animals emit short bursts of ultrasounds either from their larynx, or by clicking their tongues, and then listen to their reflections. This allows them to build a fairly accurate representation of the surrounding environment inside their brains, in very much the same way our brains construct their own representations of where we are, based on stimuli from the eyes.
Scientists say that instances in which two species have reached the same abilities are not rare in nature, but underline the fact that, most often, natural selection and evolution do not select the same paths in very different species. “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. The fact that we're able to link convergence of the DNA with a phenotype I think is unique, and in such a complex phenotype as hearing as well,” expert Dr. Stephen Rossiter, of the School of Biological and Chemical Sciences, at the Queen Mary, University of London, explains.
“We've found a whole suite of amino acid changes that are common to these two groups that have evolved in parallel, convergently,” Rossiter says. He is the author of one of the two studies published in the latest issue of the respected scientific journal Current Biology on this issue. “The results imply that there are very limited ways, if not only one way, for a mammal to hear high-frequency sounds,” University of Michigan Professor Jianzhi Zhang, the leader of the second investigation, adds.