Humpback Whale Subspecies Discovered
A new genetic study has revealed that populations of humpback whales in the oceans of the North Pacific, North Atlantic and Southern Hemisphere are actually members of separate subspecies.
The findings, published in Proceedings of the Royal Society B this week, show that these populations of humpback whales are much more distinct from one another than previously thought, and most likely evolved independently.
Humpback whales have the longest migration (between their winter and summer feeding grounds) than any mammal, traveling vast distances, and yet it appears that these groups don't cross paths.
"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," lead author, Dr. Jennifer Jackson of the British Antarctic Survey, explained in a press release.
Researchers collected genetic samples from free-swimming whales via a small biopsy dart to look at two types of their DNA: mitochondrial DNA that is inherited from the mother and nuclear DNA, which is inherited from both parents.
Mitochondrial DNA, according to Jackson, can help scientists understand how female humpbacks have migrated across the globe over the last million years, while the nuclear DNA provides insight into the movement patterns of the species as a whole.
"We found that although female whales have crossed from one hemisphere to another at certain times in the last few thousand years, they generally stay in their ocean of birth," Jackson explained. "This isolation means they have been evolving semi-independently for a long time, so the humpbacks in the three global ocean basins should be classified as separate subspecies."
Jackson hopes to conduct more genetic sequences to better understand humpback migration patterns.