Smithsonian's National Zoo & Conservation Biology Institute | Jun. 21, 2019
Unlike whales and dolphins that have lived in the marine world for more than 50 million years, sea otters have only had about 5 million years to develop the suite of adaptations necessary to survive the harsh conditions of life in the sea. What happened genetically to assist in that incredible transition?
Researchers from the Smithsonian Conservation Biology Institute along with the University of California, Los Angeles, and additional partners are studying both sea otters and comparing them to a freshwater otter species, the South American giant otter, to better understand what happens at the genetic level when a terrestrial species evolves rapidly from land to freshwater to sea life.
"We are interested in the rapid evolution of otters as it gives us a snapshot into an ongoing transition of a mammal to aquatic environments," says Klaus-Peter Koepfli, SCBI research scientist and co-author on a study published June 18 in the scientific journal, Molecular Biology and Evolution. "It is exciting to see how quickly adaptations can occur during an evolutionary transition from a terrestrial weasel-like ancestor to the marine and freshwater otters we see today."
The study, which is among the first genomic studies on otters, found that both the sea otter and giant otter have lost a considerable number of genes related to the sense of smell — a faculty that is not essential underwater. Instead, over time sea otter evolution has selected for genes that enable their marine life — such as genes to increase the bone density of their limbs to help with diving by acting as ballast (like a scuba diver's weight belt).
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