Seal Species’ Roaming Helps Mix Gene Pool

When it comes to finding females, male elephant seals have plenty of choice: Scientists have found that they will travel so extensively on occasion that a male could theoretically mate with any female in the entire species.

Reporting in the journal Science, researchers in England, Italy and Brazil sampled DNA from the southern elephant seal, Mirounga leonina. This species lives in habitats ringing Antarctica.

The scientists obtained DNA from 57 seals on the Falkland Islands and 30 on Elephant Island, then compared that with previously published DNA data from animals in other parts of the species’ range.

They found that a type of DNA called mitochondrial DNA, which is inherited only from the mother, was distinct from region to region. This was as expected, because female seals do not travel far and local genetic differences would be expected to develop over time.

However, one male on the Falkland Islands, near Argentina, was found to be closely related to animals on Macquarie Island, near Australia on the other side of the species’ range. The authors concluded that this male was born on Macquarie Island but traveled 3,200 miles to the Falklands.

Such long-distance excursions could serve to mix up the genes of even distant members of a species, keeping it genetically homogenous, the scientists concluded.