New Humpback Whale Subspecies Discovered with Genetic Analysis

First Posted: May 21, 2014 07:58 AM EDT

You'd think that we'd know all that there is to know about an animal as large as the humpback whale. But that's not the case, and a new study reveals just how much we don't know. Scientists have discovered that populations of humpback whales in the oceans of the North Pacific, North Atlantic and Southern Hemisphere are genetically distinct and should actually be recognized as a separate subspecies.

Humpback whales are known for their haunting, underwater melodies, undersea acrobatics and massive migrations. In fact, they undertake the longest migration of any mammal between their winter breeding grounds and summer feeding grounds. Yet while they cover vast distances, it appears that different humpback whale populations fail to cross each others' paths.

In order to learn a bit more about the largest animals on Earth, the researchers analyzed the largest and most comprehensive genetic dataset compiled for this species of whale. The genetic samples that they studied were collected from free-swimming whales with a small biopsy dart; they analyzed both the mitochondrial DNA, which is inherited from the mother, and the nuclear DNA, which is inherited from both parents.This allowed them to get a closer look at an animal that has captured the hearts and imaginations of people across the globe.

"Despite seasonal migrations of more than 16,000 km return, humpback whale populations are actually more isolated from one another than we thought. Their populations appear separated by warm equatorial waters that they rarely cross," said Jennifer Jackson, one of the researchers, in a news release. "The color of the bodies and the undersides of the tail (the 'flukes') of humpback whales in the northern oceans tend to be much darker than those in the Southern Hemisphere. Until this study we didn't realize that these kinds of subtle differences are actually a sign of long-term isolation between humpback populations in the tree global ocean basins."

In fact, the scientists found that although female whales have crossed from one hemisphere to another at certain times in the last few thousand years, they general stay in the ocean of their birth. This genetically isolates populations, and it appears to have created a separate subspecies.

The findings reveal a little bit more about these massive and intriguing animals. Scientists hope to conduct further genetic sequencing and analysis in order to learn more about humpback migrations in the past, and even learn a bit more about the ocean itself.

The findings are published in the journal Proceedings of the Royal Society B.

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