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Science Notes: Banded mongooses avoid close inbreeding; jellyfish quickly puts itself back together

Banded mongooses avoid close inbreeding

Most mammals that live in social groups avoid inbreeding in a simple way: They don’t mate with others in their group.

Banded mongooses, however, rarely leave their social groups. Still, they mostly manage to avoid mating with their nearest relatives.

Jenni Sanderson, an ecologist at the University of Exeter in England, and her colleagues tracked the mating behavior of more than 100 mongooses in about 10 social groups in western Uganda for 16 years. The researchers shaved a unique pattern into the fur of each mongoose for identification purposes.

Only on rare occasions did Sanderson and her colleagues observe close inbreeding, like a father mating with a daughter. The findings appear in Molecular Biology.

Inbreeding can result in smaller, less fit offspring, so it makes sense for mongooses to avoid close family members. But exactly how they identify relatives remains a mystery.

“They have individually recognizable voices,” Sanderson said. “It could be that they know their closest relatives sound most like them.”

They could also be using the sniff test. Mongooses within a social group have similar chemical secretions, Sanderson said, and it may be that close relations share a similar smell.

Jellyfish quickly puts itself back together

When a juvenile moon jellyfish loses tentacles, it rapidly reorganizes its remaining limbs to maintain symmetry, a new study says.

In the lab, researchers removed the tentacles from the translucent jellyfish. “Each time, they would start reshaping and reorganizing their bodies,” said Michael Abrams, a biologist at California Institute of Technology and an author of the new study.

The process was quick, beginning 12 hours to four days after researchers removed the tentacles. Abrams and his colleagues describe their findings in the Proceedings of the National Academy of Sciences.

The process of realignment, they found, is started by the repeated contraction of muscles that the jellyfish use continually. “It is the same mechanical force they use to swim and feed and draw food to the mouth,” Abrams said.

The only way the researchers were able to prevent the jellyfish from returning to a state of symmetry was by stopping the contractions with anesthesia.

Symmetry may be important for the moon jellies to swim and feed successfully.

– New York Times