The findings of a new study have challenged a long-held theory about bottlenose dolphins in the Mediterranean. It was thought that they were split into east and west populations, but, in fact, they are divided into coastal and offshore ecotypes that do not interact.
Common bottlenose dolphin. (Photo by Vertigem Azul / iNaturalist / CC BY-NC 4.0)
“We thought that there was a general east-west split in their populations based on quite old genetic techniques that wouldn’t be used nowadays,” said lead author and marine biologist at the University of Exeter, Daniel Moore, to Discover Wildlife. “We started the study wanting to understand that east-west split a bit more, but using modern techniques, and what we found was just not expected at all.”
Beyond geographical differences, Moore said that the dolphin populations can be divided into two different ecotypes: coastal and offshore. This is similar to what we find in orcas, he said. The findings, published in the journal Molecular Ecology, show that the two ecotypes have different genetics, social structures and “languages”.
Furthermore, the dolphins found in Sicily were the same offshore group as those found in the Azores, a long distance away, and did not interact with the coastal dolphins, even though they swam through the same waters. “These dolphins have really high gene flow between Sicily and Azores, but virtually nothing between those dolphins and all the coastal populations they must pass along the way,” said Moore. According to the researchers, the offshore dolphins are larger and behave differently.
As bottlenose dolphins are a protected species in the Mediterranean, knowledge of these two different ecotypes helps experts understand the different threats they may face in each of their habitats (such as bycatch) and come up with appropriate conservation measures.
