Killer Whales Split into Three Separate Species
Sunday, April 25 2010 @ 09:11 PM EDT
Contributed by: jkr
April 25, 2010
Using genetic evidence scientists have discovered that the world’s killer whales, also known as orcas (Orcinus orca), likely represent at least three separate species.
Scientists have long thought that there may in fact be more than one species of killer whales due to behavior difference, small physical differences, and the animals' primary food source: fish or seals.
Scientists analyzed genetic samples from 139 killer whales and announced their findings in the journal Genome Research.
"The genetic makeup of mitochondria in killer whales, like other cetaceans, changes very little over time, which makes it difficult to detect any differentiation in recently evolved species without looking at the entire genome," explains Phillip Morin, lead author and geneticist at NOAA's Southwest Fisheries Science Center in La Jolla, California. "But by using a relatively new method called, 'highly parallel sequencing' to map the entire genome of the cell's mitochondria from a worldwide sample of killer whales, we were able to see clear differences among the species."
Morin and his team have identified at least three separate species of orca: a fish-eating species in Antarctica, another in Antarctica that primarily feeds on seals, and a third species that hunts marine mammals in the North Pacific. Further analysis may reveal that killer whales—long classified as a single species—are even more diverse than these three.