Killer Whales Splitting into Two Species?

[The Minx]

Link

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."

Cool to see this kind of things happening.


As with all public websites, the comment section is hilariously inane as usual:

[This user is an administrator] Mike Coville
Let me know when a whale gives birth to a another whale that can walk on land and then we can talk about a new species, until then it is still a whale.

This is the kind of insanity that is killing science.

[LadyTevar]

This Mike Coville is a frakkin' IDJIT.

This is fantastic news, as it's specization happening before our very eyes! I have to wonder if the size difference has something to do with diet -- are they bigger to better catch the dolphins and small whales, or is their size because they are eating larger prey? Wouldn't a smaller body cut through the water easier, which would make sense when eating agile swimmers like fish and seals. So a larger body would be useful in overpowering small ceta like dolphins and beluga.

I know that orca run in maternal pods, with the older females teaching the babies their knowledge of hunting and other skills. Such pods even have their own 'dialect' of whalesong, distinct to even the human ear from another pod. The young males chased off when they start reaching breeding age. Juvie males make their own pods until they reach full maturity, then may pair off with just one or two companions to find mates.

So, to my mind, the question would be if Type 1 and Type 2 are still interbreeding. Since Type 2 are swimming around the English waters, while the Type 1 are living around the US and Canada, do the males ever 'cross the pond' to mate with the other pods? Or has the Atlantic separated the two family lines enough that they are only mating amongst themselves?

And what does this mean for the Pacific and Antarctic orca? Are they also going to show a genetic break between the Antartic seal hunters, and those swimming the warmer waters of the Pacific coast?

Pity this article draws more questions than answers... but I guess that's what Good Science does.

[Comrade Tortoise]

w that orca run in maternal pods, with the older females teaching the babies their knowledge of hunting and other skills. Such pods even have their own 'dialect' of whalesong, distinct to even the human ear from another pod. The young males chased off when they start reaching breeding age. Juvie males make their own pods until they reach full maturity, then may pair off with just one or two companions to find mates.

Not just different dialects... bottlenose dolphins can convey complex information and their calls probably function as language. I dont imagine orca are any different.

So, to my mind, the question would be if Type 1 and Type 2 are still interbreeding. Since Type 2 are swimming around the English waters, while the Type 1 are living around the US and Canada, do the males ever 'cross the pond' to mate with the other pods? Or has the Atlantic separated the two family lines enough that they are only mating amongst themselves?

The answer is "probably not" The whales are fairly philopatric, they do not disperse far. If they did they would not have access to reliable food sources.