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Revealing the evolutionary history of threatened sea turtles
October 16, 2008It's confirmed: Even though flatback turtles dine on fish, shrimp, and mollusks, they are closely related to primarily herbivorous green sea turtles. New genetic research carried out by Eugenia Naro-Maciel, a Marine Biodiversity Scientist at the Center for Biodiversity and Conservation at the American Museum of Natural History, and colleagues clarifies our understanding of the evolutionary relationships among all seven sea turtle species.
Naro-Maciel and colleagues used five nuclear DNA markers and two mitochondrial markers to test the evolutionary relationships of all species of marine turtles-leatherback, flatback, green, hawksbill, loggerhead, Kemp's Ridley, and Olive Ridley-and four 'outgroups,' or more distantly related animals. The results formed a well-supported phylogenetic tree, or cladogram, that tells the story of sea turtle evolution and is reported in the journal Molecular Phylogenetics and Evolution.
"The evolution of a specialized diet appears to have occurred three times, independently," says Naro-Maciel. "Many sea turtles are carnivorous generalists. However, hawksbills tend to have a diet of glass-they eat toxic sponges-while the leatherback consumes jellyfish and the green grazes mainly on algae or sea grass." Each of the species with specialized diets is positioned uniquely in the evolutionary tree.
Naro-Maciel and colleagues confirmed that one major group of sea turtles includes sister species flatback and green turtles (one carnivorous and the other herbivorous), while another clade is formed by the hawksbill, loggerhead, Kemp's Ridley and Olive Ridley turtles. The leatherback is confirmed as the most basal of all the sea turtles, and the Eastern Pacific green turtle-thought by some to be a separate species-falls within the green turtle species. The branches of this evolutionary tree can be calibrated with time using the new phylogeny and DNA data: Even though the ancestor of all sea turtles arose over 100 million years ago, the separation between the flatback and green turtles happened about 34 million years ago.
Determining the evolutionary relationships among sea turtles as well as the species identity of different populations of this highly migratory group of animals has implications for conservation. All sea turtles are included on the IUCN's Red List of Threatened Species, some of them as critically endangered, and an accurate understanding of this highly migratory group is important.
"These research results are another example of the importance of using systematics and taxonomy as a way to prioritize conservation efforts and strategies," says George Amato, Director of the Sackler Institute for Comparative Genomics at the Museum and an author of the article. "Only with these detailed studies can we better conserve the naturally occurring evolutionary novelty and patterns of genetic diversity for endangered species."
American Museum of Natural History
Naro-Maciel and colleagues confirmed that one major group of sea turtles includes sister species flatback and green turtles (one carnivorous and the other herbivorous), while another clade is formed by the hawksbill, loggerhead, Kemp's Ridley and Olive Ridley turtles. The leatherback is confirmed as the most basal of all the sea turtles, and the Eastern Pacific green turtle-thought by some to be a separate species-falls within the green turtle species. The branches of this evolutionary tree can be calibrated with time using the new phylogeny and DNA data: Even though the ancestor of all sea turtles arose over 100 million years ago, the separation between the flatback and green turtles happened about 34 million years ago.
Determining the evolutionary relationships among sea turtles as well as the species identity of different populations of this highly migratory group of animals has implications for conservation. All sea turtles are included on the IUCN's Red List of Threatened Species, some of them as critically endangered, and an accurate understanding of this highly migratory group is important.
"These research results are another example of the importance of using systematics and taxonomy as a way to prioritize conservation efforts and strategies," says George Amato, Director of the Sackler Institute for Comparative Genomics at the Museum and an author of the article. "Only with these detailed studies can we better conserve the naturally occurring evolutionary novelty and patterns of genetic diversity for endangered species."
American Museum of Natural History
Sea Turtles Current Events and Sea Turtles News RSSRemotely Operated Vehicles and Satellite Tags Aid Turtle Studies
Researchers are using a remotely operated vehicle (ROV) and satellite-linked data loggers to learn more about turtle behavior in commercial fishing areas and to develop new ways to avoid catching turtles in fishing gear.
Loss of top predators causing surge in smaller predators, ecosystem collapse
The catastrophic decline around the world of "apex" predators such as wolves, cougars, lions or sharks has led to a huge increase in smaller "mesopredators" that are causing major economic and ecological disruptions, a new study concludes.
Barcoding endangered sea turtles
Conservation geneticists who study sea turtles have a new tool to help track this highly migratory and endangered group of marine animals: DNA barcodes.
Wildlife faces cancer threat
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NOAA Report Finds Threats to California's Cordell Bank Marine Sanctuary
A new NOAA report on the health of Cordell Bank National Marine Sanctuary indicates that the overall condition of the sanctuary's marine life and habitats is fair to good, but identifies several emerging threats to sanctuary resources.
Bone bed tells of life along California's ancient coastline
In the famed Sharktooth Hill Bone Bed near Bakersfield, Calif., shark teeth as big as a hand and weighing a pound each, intermixed with copious bones from extinct seals and whales, seem to tell of a 15-million-year-old killing ground.
UBC researcher solves century-old enigma of prehistoric marine mass grave
Good old-fashioned detective work has turned up the first conclusive explanation for the origin of a massive bonebed in southern California, according to a new study led by a UBC paleontologist.
Scientists identify world's largest leatherback turtle population
An international team of scientists has identified a nesting population of leatherback sea turtles in Gabon, West Africa as the world's largest.
Polarized light pollution leads animals astray
Human-made light sources can alter natural light cycles, causing animals that rely on light cues to make mistakes when moving through their environment.
Zoologists: Sea snakes seek out freshwater to slake thirst
Sea snakes may slither in saltwater, but they sip the sweet stuff. So concludes a University of Florida zoologist in a paper appearing this month in the online edition of the November/December issue of the journal Physiological and Biochemical Zoology.
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Cloud b Twilight Sea Turtle - Constellation Night Light by Cloud b Enjoy a peaceful night sleep under Twilight Sea Turtle's starry night sky. This fun and educational nightlight is designed to help children sleep easier and also help bring awareness to endangered sea animals. Twilight Sea Turtle's beautiful shell illuminates in 3 soothing colors, while also highlighting 5 endangered sea friends...the Blue Whale, California Sea Otter, Knysna Seahorse, Leatherback Turtle and Vaquita Dolphin. The Twilight Storybook includes a Twilight Sea Turtle story that teaches children about endangered sea animals, a helpful Star Guide and an adoption certificate. A portion of the proceeds from Twilight Sea Turtle will be donated by Cloub b to an international conservation organization. Features: Night sky projection on ceiling Stars project in Ocean Blue, Emerald... |
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