Sea turtle evolution research


This video says about itself:

Sea Snakes and Turtles – Reef Life of the Andaman – Part 20.

From the American Museum of Natural History:

Revealing the evolutionary history of threatened sea turtles

New research from the American Museum of Natural History shows that specialized diets arose independently

It’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.”

High mortality of loggerhead turtles due to bycatch, human consumption and strandings at Baja California Sur, Mexico, 2003 to 2007: here.

Turtle genome analysis sheds light on turtle ancestry and shell evolution: From which ancestors have turtles evolved? Here.

Green turtle research here.

Flatback turtles arrive for nesting season: here.

Oceanic superhighway from Indonesia to Australia revealed by Green turtle: here.

5 thoughts on “Sea turtle evolution research

  1. Turtle egg seekers hope for large find
    Officials: 200 nests could be on local beaches

    * By Jaime Powell
    * Posted March 20, 2010 at 8:43 p.m.

    CORPUS CHRISTI — The Easter Bunny has competition on North Padre Island where more than 100 grown-ups are preparing to look for a different sort of egg.

    Searchers are looking for faint, 2-foot wide trails in the sand that will lead them to endangered Kemp’s ridley sea turtle eggs.

    “It’s a lot more fun than Easter,” said Dan Tholen, a veteran egg chaser. “They are quite a bit rarer than Easter eggs were as a kid.”

    The Texas coast has seen a record number of turtle nests, jumping from 11 in 2001 to 197 in 2009 as the result of preservation efforts. Every year hundreds of tourists watch during public releases as Donna Shaver, chief of sea turtle science and recovery at Padre Island National Seashore, and volunteers shepherd tiny turtles safely into the water and out of the clutches of seagulls.

    The Texas nesting season typically runs April to July. Some female turtles breed annually and nest an average of one to four times in a season.

    Tholen has been a turtle patrol volunteer for three of the past four years. He and a couple of dozen others went to Sea Turtle School on Wednesday and Thursday.

    They learned how to spot nests, how to take care of nesting female turtles and how to drive the patrol vehicles used for searches.

    Tholen found eggs his second day three years ago. Others hunt for months or years and never see a sign of a turtle or nest.

    “It feels excellent to see things few people ever see,” Tholen said.

    Volunteers work five-hour shifts starting as early as 6:30 a.m., seven days a week. Each shift covers about 20 miles of beach. If they are lucky enough to find a nest, which usually contains about 100 eggs, it is loaded into a Styrofoam cooler and hauled to an incubator at seashore headquarters. Hatching takes several weeks.

    The 200 or so nests local searchers hope to find this year in Texas are a far cry from the 40,000 Kemp’s ridley turtles that experts estimate nested in 1947 on a stretch of beach near Rancho Nuevo, Mexico.

    Kemp’s ridley turtles were decimated by a combination of factors, including environmental issues, shrimpers’ nets and natural predators such as sharks or humans, who have made cowboy boots out of their skin, eaten their flesh and valued the eggs for food and their supposed aphrodisiac qualities, according to conservation agencies.

    Protection efforts started in the 1960s, but there were 5,000 nests in Mexico by 1968. The turtles were listed as an endangered species in the U.S. in 1970.

    The U.S. and Mexico have successfully coordinated nest protection efforts, Shaver said. In 2009, the total number of nests recorded at Rancho Nuevo exceeded 20,000 from about 8,000 females. In Texas, from 2002 through 2009, a total of 771 Kemp’s ridley nests have been documented, according to the U.S. Fish and Wildlife Service.

    Shaver believes this year could be a banner year for the turtles on the South Texas coast.

    “They are still the most endangered turtles in the world, but I’m excited their numbers are increasing,” Shaver said.

    Clark Williams, a retired dentist, who is starting his first year on turtle patrol, is confident he will find a nest. He hopes to spend at least 10 hours a week looking.

    But for Williams, it’s not about the egg.

    “I have a fondness for everything in nature,” he said. “And I’m very concerned about the future. If we don’t take care of our stuff we are going to lose it before our grandchildren get to enjoy it.”

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