Killer Whales Splitting into Two Species?

Killer Whales in the in the North Atlantic Ocean come in two different flavors, and could be in the process of splitting into two species, according to new research by a team of European scientists.

Orcas in different regions like the Pacific and Antarctic are known to have different diets, but are recognized as belonging to the same species, Orcinus orca. Researchers have now found that two populations living in the waters around Britain differ not only in what they eat, but also in size and genetic makeup.

According an article today on the BBC website, researchers showed that "type 1" whales had significantly more tooth wear than "type 2" whales, which also tended to be two meters (6.6 feet) longer.

The patterns of tooth wear suggest that type 1 whales are generalists, feeding on a combination of seals and fish. On the other hand, type 2 whales eat only marine mammals like dolphins and other small whales.

A genetic analysis showed that type 2 whales, which tend to show up off the coasts of Scotland and Ireland, are more closely related to Antarctic orcas than the type 1 group, which are found across the eastern North Atlantic. From the article:

Comparing the findings with studies on killer whales around the world shows that killer whales have radiated to fill different ecological niches.

"It's similar to how Darwin's finches have adapted to different ecological roles in the Galapagos, but on a larger scale," Dr. [Andy] Foote [of the University of Aberdeen in the UK] notes.

He suggests this could be an important discovery for the future of the animals.

"They seem to have occupied completely different ecological niches and have started to diverge morphologically. This divergence may eventually lead to the two types becoming different species."

Image: CBC/Robert Pittman