Killer whales may not be just one species but rather four or more, with each hunting different prey, living in their own kinds of groups, prowling their own unique ranges and speaking in distinct ways, according to new genetic research.
Until now, however, scientists had not proved different species of killer whales existed. Genetic analyses had been inconclusive because scientists hadn’t mapped the entire genome of the whales’ mitochondria.
[B]y using a relatively new method called highly parallel sequencing to decipher the entire genome of mitochondria from a worldwide sample of 139 killer whales from the North Pacific, the North Atlantic and the oceans surrounding Antarctica, “we were able to see clear differences among the species,” explained researcher Phillip Morin.
In Antarctica, there are actually two different species that are distinct enough from orca in other parts of the world that they probably diverged genetically about 150,000 years ago. One specializes in knocking seals off of ice; the other, the “Ross Sea killer whale” specialized on fish beneath the ice.
The transients of the North Pacific, marked by sparser vocalizations, less tightly-knit pods, and a preference for marine mammals for their prey, are even farther remote in kinship, having split off around 700,000 years ago.
Results for the residents of the Pacific, Antarctica, and the North Atlantic are murkier; these may be the same species, sub-species, or different species, but until more samples are acquired researchers aren’t sure.
And, well, do you want to be the one to ask a killer whale in the wild for a saliva sample?