Once in a great while, snails successfully crossed Central America by flying over Mexico stuck to the legs or riding on the bellies of shorebirds, a new study has found.
“Just as people use airplanes to fly overseas, marine snails may use birds to fly over land,” said Mark Torchin, staff scientist at the Smithsonian in Panama.
“It just happens much less frequently. There’s also a big difference between one or two individuals ending up in a new place, and a really successful invasion, in which several animals survive, reproduce and establish new populations,” he added.
The discovery of the hitchhiking snails has broad implications. “Not only snails, but many intertidal organisms may be able to ‘fly’ with birds,” said first author of the study, Osamu Miura, assistant professor at Japan’s Kochi University and former postdoctoral fellow at the Smithsonian Tropical Research Institute in Panama.
Scientists at the Smithsonian have long been interested in how the rise of the Central American land bridge more than 3 million years ago drove speciation and increased biodiversity.
It formed a barrier between marine species, some of which evolved in their new surroundings, becoming new “sister” species that could no longer mate with their former relatives.
By studying the genetics of two sister species of Horn Snails, Cerithideopsis californica and C. pliculosa, collected at 29 different locations in mudflats and mangrove habitats from California to Panama on the Pacific and from Texas to Panama on the Atlantic, the researchers discovered that, about 750,000 years ago, these snails invaded the Atlantic from the Pacific, and then, about 72,000 years ago, Atlantic populations returned to invade Pacific shores.
The study has been published in Proceedings of the Royal Society: B.