Loggerhead sea turtle seem to break this common wisdom. A new study published by Current Biology by scientists at the University of North Carolina at Chapel Hill shows that their genetic similarities are closely related to the magnetic field in the nests where they were born.
The study’s lead author, J. Roger Brothers, said that magnetic imprinting is a better indicator of genetic similarity, and it is better than turtle groups that live in close proximity to each other or in similar environments.
“A lot of different animals, including sea turtles, will detect the Earth’s magnetic field and then get navigation information from it and use it to find their way, or find their way through long-distance migration,” Brothers said.
Turtles are likely to “stamp” the magnetic field of their nested area at a very young age, even before they hatch.
This is like a compass, he said, even if they leave the east coast of the United States, and travel within a long distance, in some cases still flying to Africa.
Brothers said: “Turtles can obtain position information or understand their position in the world based on the local magnetic fields they sense.” They are using it to find their way home.
Interestingly, turtles returning to their birthplace are genetically similar to each other.
But this is a turning point: It seems sometimes that they will be confused. Brothers said some of Florida’s beaches are on both sides of the peninsula but have similar magnetic fields.
And these turtles seem to be more disoriented and go to the beach with familiar magnetic fields and species, instead of going to a beach near a different magnetic field.
This may be why the brothers’ study found that when they came from beaches with magnetic similarities, the turtle population was most likely genetically similar.
“Through these navigation errors, we can see where the population structure is, regardless of the geographical distance or environmental similarity between the two nesting beaches,” he said.
“The difference in Earth’s magnetic field is a truly powerful predictor of genetic similarity or difference between two nesting populations.”
Scientists used data collected by 834 nested women at 20 different locations on the southeast coast of the United States.
Brothers said: “It’s nice to know why animals go to certain places, especially to reproduce. These findings have a certain impact on the protection work – if the magnetic field of turtle nesting area is destroyed or changed, it may be detrimental to animals.
“This can be any large hotel or seawall with rebar and metal that can disrupt the magnetic field,” Brother added.
Many animals use the Earth’s magnetic field for navigation. Brothers stated that for other species of sea turtles, as well as herring, seals and certain sharks, genetic similarities of animals with similar magnetic characteristics may also be found.