By MATT WALKER - BBC EARTH NEWS WEBSITE
Added: Thu, 02 Sep 2010 12:21:33 UTC

Thanks to Gustavo.wolf for the link.

Orcas, commonly known as killer whales, are still evolving, and quickly.

Researchers have discovered that two distinct types of orca, a large and a pygmy form, are rapidly diverging, evolving away from each other.

The scientists' study reveals each type of orca carries a unique gene mutation that benefits its particular lifestyle.

The genetic change has occurred in the past 150,000 years, adding to evidence that the orcas are quickly evolving into two distinct species.

Details of the research are published in the journal Biology Letters by an international team of scientists led by orca expert Dr Andrew Foote of the Natural History Museum of Denmark based at the University of Copenhagen.

Energetic lifestyles

The orcas studied live in Antarctic waters, and are known as type B and type C orcas.

Type Bs are one of the largest forms of orca known and primarily feed on seals.

Type Cs, in contrast, are known as a dwarf-form of orca, and feed mainly on fish.

These differences in size and diet, as well as each type having distinct markings, has led Dr Foote and colleagues to previously propose that they could be two separate species.

Genetic evidence now backs that idea.

Read full story here.

TAGGED: EVOLUTION, SCIENCE