SCIENCE LAB SPECIAL : GENETIC STUDIES

 

They Get Around : Genetic studies reveal blue whale family secrets : In 2014, nine blue whales died after being trapped by ice near Newfoundland, Canada. Two of their carcasses washed ashore.

Nearly a decade after their deaths, researchers have analyzed the DNA of the beached whales - along with samples collected from 26 other blue whales - to create the most accurate picture to date of the structure of the North Atlantic Population.

The results, published in the journal Conservation Genetics, reveal peculiar migration patterns and cross species matings.

A possible ticking time bomb that they feared to find in blue whale demographics didn't show up. But that doesn't mean it isn't there.

The global population of blue whales was seriously depleted by industrial whaling in the early 20th century. In a declining population, rates of inbreeding can rise,which can reduce the variety in a population gene pool and increase the risk of species extinction.

With fewer than 3,500 adult blue whales remaining in the North Atlantic, scientists expected to find such a genetic bottleneck. At first, they were surprised when their analysis showed no signs of one.

They suggest that gap may result from the length of time it takes blue whales to reproduce - about 30 years to go from one generation to the next. '' It probably hasn't been enough time to really see a bottleneck effect,'' said Mark Engstrom, a genomicist in Toronto who supervised the research effort.

But if the population doesn't grow over the next century, Dr. Engstrom said a bottleneck to emerge.

Whalers historically thought that blues in the North Atlantic were split into distinct east and west population. But the whales DNA tells a different story. Dr. Engstrom's team found evidence for east-west intermingling.

More surprising, there is also considerable evidence of mating with smaller fin whales, even though the two species aren't very closely related.

The resulting hybrids apparently produce young themselves, though possibly only by mating with blue whales, not with fin whales. [ Darren Incorvaia ].