Researchers confirm that narwhals and beluga whales can interbreed

The hybrid skull has a set of long, spiral, and pointed teeth, which are angled horizontally. Credit: Mikkel Høegh Post

A team of researchers from the University of Copenhagen has compiled the first and only evidence that narwhals and beluga whales can reproduce successfully. Analysis of DNA and stable isotopes from an abnormal skull at the Danish Museum of Natural History enabled researchers to confirm the existence of a narwhal-beluga hybrid.

For almost thirty years, a strange whale skull has gathered dust in the collections of the Natural History Museum of Denmark. Now, a team of researchers has determined the reason for the skull’s unique characteristics: it belongs to a narwhal-beluga hybrid.

A Greenlandic hunter shot the whale in the 1980s and was intrigued by its odd appearance. So he kept the skull and placed it on the roof of his tool shed. Several years later, Professor Mads Peter Heide-Jørgensen of the Greenland Natural Resources Institute visited the colony and also immediately recognized the strange features of the skull. He questioned the hunter about the anomalous whale he had shot and sent the skull to Copenhagen. Since then it has been kept in the Zoological Museum, which is part of the Danish Museum of Natural History.

“As far as we know, this is the first and only evidence in the world that these two species of arctic whales can interbreed. Based on the intermediate shape of the skull and teeth, it has been suggested that the specimen could be a narwhal-beluga hybrid, but this could not be confirmed. Now we are providing the data which confirms that yes, it is indeed a hybrid “, explains Eline Lorenzen, evolutionary biologist and curator at the Danish Museum of Natural History at the University of Copenhagen Lorenzen led the study, which was published today in Scientific reports.

Using DNA and stable isotope analyzes, scientists determined that the skull belonged to a first-generation male hybrid between a female narwhal and a male beluga.

Weird chops set

The hybrid’s skull was considerably larger than that of a typical narwhal or beluga. But the teeth were markedly different. While narwhals have only one or rarely two long, spiral tusks, belugas have a set of uniform conical teeth aligned in straight rows. The hybrid skull has a set of long, spiral, pointed teeth, which are angled horizontally.

“This whale has bizarre teeth. Isotope analysis allowed us to determine that the animal’s diet was totally different from that of a narwhal or a beluga – and it is possible that its teeth influenced its foraging strategy. While the other two species foraged in the water column, the hybrid was a bottom dweller, “according to Mikkel Skovrind, a Ph.D. student at the Natural History Museum and first author of the article.

Danish researchers confirm that narwhals and beluga whales can interbreed

Illustration of the appearance of the hybrid. Credit: Markus Bühler

Researchers don’t know what prompted the two species to mate, but it suggests a new phenomenon:

“We analyzed the nuclear genomes of a narwhal and a beluga, but we see no evidence of crossbreeding for at least 1.25 million years of their evolutionary history. Thus, the cross between species appears to be a very rare or new event. To my knowledge, this has never been observed or recorded before, “explains Eline Lorenzen.

Gems among the museum’s collections

Lorenzen points out that she and her colleagues used new analytical methods that were only recently developed.

“There are real gems in the world’s natural history collections that can provide us with key information about the evolution and diversity of life on Earth. It’s amazing when material, like this skull, which has been stored in our collection for decades, can be revisited with new methodologies to gain new biological knowledge, ”explains Eline Lorenzen.

Mikkel Skovrind adds: “It would be interesting to know if similar hybrid whales have been spotted elsewhere. “

Facts

  • By extracting DNA from the anomalous whale skull and comparing it to a narwhal and beluga genetic reference panel, the researchers established the whale’s genomic affiliation.
  • The researchers analyzed the reference stocks of narwhal and beluga for stable isotopes and compared them to the isotopic values ​​of the hybrid skull. By measuring the concentrations of carbon and nitrogen in the bones, the researchers were able to discern whether the whale’s diet consisted of food from the water column or from the seabed. The isotopes showed that the food choices of the hybrid whale were very different from those of the narwhal or beluga.
  • Narwhals and beluga whales are the only endemic tooth whales in the arctic region. Although they are the closest relatives to each other and roughly equal in size, the two species differ in morphology and behavior. Narwhals are characterized by their long, spiraling tusks and greyish-brown mottled pigmentation, while belugas have two rows of uniform teeth and adults are completely white. Narwhals are food choice specialists and beluga whales are generalists.
  • The research is a collaboration between the Danish Museum of Natural History at the University of Copenhagen, the Greenland Institute of Natural Resources and the Department of Anthropology at Trent University (CA).
  • The research is supported by the Carlsberg Foundation, the Villum Fonden Young Investigator program and the Canada Research Chairs program.

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More information:
Mikkel Skovrind et al. Hybridization between two cetaceans from the High Arctic confirmed by genomic analysis, Scientific reports (2019). DOI: 10.1038 / s41598-019-44038-0

Provided by the University of Copenhagen

Quote: Researchers Confirm Narwhals and Beluga Whales Can Interbreed (June 20, 2019) Retrieved October 14, 2021 from https://phys.org/news/2019-06-narwhals-belugas-interbreed.html

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