Bats and Dolphins Share Hidden, Genetic Similarities: Independent Evolution

What do bats and dolphins have in common? More than you might think. The evolution of similar traits in different species is known as convergent evolution. Now, scientist have discovered this type of evolution is not only widespread on the physical level, but also the genetic level.

In order to examine convergent evolution a bit more closely, researchers decided to focus on echolocation. This particular complex physical trait involves both the production and reception of ultrasonic pulses to detect unseen obstacles or prey. This attribute has evolved separately in different groups of bats and cetaceans, including dolphins. Needless to say, this makes it the perfect trait to study.

In all, the researchers compared genomic sequences of 22 mammals, including the genomes of bats and dolphins. They sifted through millions of letters of genetic code using a computer program developed to calculate the probability of convergent changes occurring by chance so that they could identify the "odd-man-out" genes.

"We had expected to find identical changes in maybe a dozen or so genes but to see nearly 200 is incredible," said Joe Parker, one of the researchers, in a news release. "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."

That's not all they found, either. The scientists discovered that signs of convergence among bats and the bottlenose dolphin were seen in many genes previously implicated in hearing or deafness. The fact that these molecular signals of convergence were so widespread greatly adds to the understanding of genome evolution.

"These results could be the tip of the iceberg," said Stephen Rossiter, one of the researchers, in a news release. "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."

The findings reveal a little bit more about the process of evolution. In addition, it shows that traits can evolve independently of one another in two drastically different species. This, in turn, could allow scientists to better understand how other species might have evolved in the past.

The findings are published in the journal Nature.