Catherine Griffin reports that scientists have determined 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. She quotes the article “Global diversity and oceanic divergence of humpback whales (Megaptera novaeangliae),” recently published in the Proceedings of the Royal Society of Biological Sciences. [Now I am curious; which subspecies is the one we’ve religiously watched as they travel along the northern coast of Puerto Rico?] See excerpts here, with a link to the full article below:
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 are published in the journal Proceedings of the Royal Society B.