Evolution of whale size linked to diet

May 20, 2010

(PhysOrg.com) -- The wide range of body sizes among whales arose early in their evolution and was associated with changes in diet, according to a new study by researchers at UC Davis and UCLA. The study appears in today's (May 20) issue of the journal Proceedings of the Royal Society B.

"There's a huge size variation in cetaceans," said Samantha Price, a postdoctoral researcher at the UC Davis Department of Evolution and Ecology and co-first author on the paper. They range from dolphins and porpoises to the largest animal that has ever lived, the .

Modern whales appeared in the oceans about 30 million years ago, after a more ancient group of whale species became extinct. But scientists do not know whether modern whales evolved fairly rapidly, becoming diverse in size as they adapted to new ecological niches, or if the differences between groups appeared more gradually over time.

Price, then a researcher at the National Center at Duke University, and co-authors Graham Slater, Francesco Santini and Michael Alfaro at UCLA constructed a "family tree" for whales based on genetic data, and used it to understand how the traits of diet and size evolved.

Fish-eaters, mainly dolphins and porpoises, tend to be small. Whales that feed on squid are larger, probably because they need to make long, deep dives to catch their prey, Price said. Plankton-feeding whales, such as the blue whale, are the largest of all. These differences hold up within groups -- dolphin species that eat squid are bigger than those that eat fish. Orcas are something of an outlier, as they eat a lot of fish but are large; but they also eat mammals such as seals and sea lions, Price noted.

A model of whale evolution that makes size dependent on gave the best fit to the data, Price said.

Explore further: High-pitched sounds cause seizures in old cats

Related Stories

Humpback whales have brain cells also found in humans

Nov 27, 2006

Cetaceans, the group of marine mammals that includes whales and dolphins, have demonstrated remarkable auditory and communicative abilities, as well as complex social behaviors. A new study published online November 27, 2006 ...

Whales evolved biosonar to chase squid into the deep

Sep 05, 2007

Behind the sailor's lore of fearsome battles between sperm whale and giant squid lies a deep question of evolution: How did these leviathans develop the underwater sonar needed to chase and catch squid in ...

Getting a leg up on whale and dolphin evolution

Sep 24, 2009

When the ancestors of living cetaceans—whales, dolphins and porpoises—first dipped their toes into water, a series of evolutionary changes were sparked that ultimately nestled these swimming mammals into ...

Recommended for you

High-pitched sounds cause seizures in old cats

1 hour ago

When the charity International Cat Care asked veterinary neurologists at Davies Veterinary Specialists, UK, for help with several enquiries it had received regarding cats having seizures, seemingly in response ...

Bumblebees use nicotine to fight off parasites

6 hours ago

Researchers from Queen Mary University of London (QMUL) and Royal Holloway, University of London (RHUL), gave bumblebees the option to choose between a sugar solution with nicotine in it and one without. ...

ANZAC grevillea hybrid marks centenary celebrations

7 hours ago

Through an intense breeding program of native flora, Kings Park botanists have provided the Western Australian RSL with a commemorative grevillea (Proteaceae) in time for the Anzac Centenary.

Secret life of penguins revealed

11 hours ago

To mark World Penguin Day (25 April 2015) citizen science project Penguin Watch will release 500,000 new images of penguins and reveal secrets from a year of spying on penguins. ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.