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Oh, the tales these whale lice could tell.
Studying the thumbnail-sized lice that cling to the skin of certain whales, University of Utah biologists have helped tease out the evolutionary history of the ocean-dwelling giants.
Genes of the lice, which are actually crustaceans called cyamids, offer evidence that whales known as right whales split into three different species about 5 million years ago. This time frame is also when the Atlantic and Pacific oceans split following the rise of the Isthmus of Panama, U. biologist Jon Seger said.
The lice gene-based study will appear in the October edition of the journal Molecular Ecology. U. researchers worked with colleagues from more than a dozen institutions in the United States, Argentina, South Africa and Australia.
Right whales, which can grow to weigh 70 tons, got their name because these slow, blubber-laden beasts made easy targets for early Basque whaling crews and later commercial ventures. When the mammoth creatures died, their carcasses floated.
"They were so easy to kill," Seger said.
By the end of the 19th century, the northern ocean right whales became commercially extinct. An estimated 350 ply the waters of the North Atlantic today while roughly 200 still make the North Pacific their home. The right whales of the southern oceans boast a population as high as 10,000.
Studying whale genes is difficult because the huge creatures live up to several decades and are slow to evolve. Lice have short lifespans, so genetic changes crop up faster in the tiny, crab-like creatures, said Zofia "Ada" Kaliszewska, a former U. student and study author.
The whales' evolutionary history was not what researchers had in mind when they started studying the lice, however.
Vicky Rowntree, a biologist who splits her time between the U. and the Ocean Alliance/Whale Conservation Institute, in Lincoln, Mass., set out to learn about right whale social patterns by examining lice genes.
She wanted to examine the lice living on individual whales to learn about their social contacts. When whales interact and make contact, lice can switch hosts.
More than 7,000 lice, divided among three species, can be found riding any given right whale. When researchers studied lice from individual whales, each louse appeared genetically different. Scientists couldn't link the genes of one louse to a single whale, which meant the lice would not help identify social patterns.
But the disappointing result had an upside: As it turns out, whale lice are prolific migrators.
And they leap from whale to whale at great personal risk, because they can't survive away from their host. Sometimes lice may have a split-second to fling themselves to a new host.
"If you miss, you're in the drink," Seger said, "and you're dead."
Of course from a survival standpoint, being caught on a dying whale, can spell doom, too. Lice interested in maintaining their genetic lineage appear to have no choice but to keep whale hopping, even if it means finding themselves marooned on an even older host, Seger said.
These traveling lice offer another research benefit - a hundred lice taken from a single whale can represent critters from dozens and dozens of other whales.
"It's a bonanza of whale lice," he said.
Seger and Rowntree, a husband-wife research team, along with other scientists have asked marine biologists to grab lice from beached or stranded whales. Marine biologists often hear of beached whales within hours and rush to the scene to help or collect data.
Such lice samples from around the globe helped researchers determine that three distinct species of right whales evolved. If only one right whale species existed, then all whales would carry the same three species of lice.
But genetic investigation suggests the existence of nine distinct lice species, or three sets of three lice, one set for each species of right whale. Each set of three lice species spent millions of years evolving on their specific right whale species.
Genetic information from the "whale riders" may also help determine whaling's role in making the North Atlantic and North Pacific right whales endangered.
The evidence indicates that commercial whaling is the main reason the mammoth creatures are not genetically diverse today. Researchers previously have argued the whales had a historically small population to explain the lack of diversity.
"They were hunted to near-extinction recently," said Kaliszewska, who is now a graduate student at Harvard University.
This new lice-based research offers evidence that great numbers of right whales roamed the northern oceans before whaling began in the 11th century.
And as researchers develop new ways to read lice genes, there will be more whale stories to come.