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Genetic studies conducted by two Brazilian researchers show that animals can "betray" their places of birth, their partners and even their species.
Sea turtles are not as faithful animals as previously thought. They can "betray" their places of birth and spawning (not always returning to the same, as is generally believed), their partners and even their species.
This is at least what two genetic studies on the populations of these reptiles from different parts of the world, including Brazil, were conducted by two Brazilian researchers, from the Federal Universities of Espírito Santo ( UFES) and Rio Grande (FURG). Rio Grande do Sul.
The geneticist Sarah Vargas, of UFES, began her studies on sea turtles in 2005, when she began her PhD at the Federal University of Minas Gerais (UFMG).
"I have worked with the five species present in Brazil, but mainly in leatherback turtles (Dermochelys coriacea) and deer (Eretmochelys imbricata), two endangered species," he says. "I studied samples from Brazil and the Indo-Pacific, but I used published genetic sequences from around the world."
Her most important research began in 2008, when she spent six months in the laboratory of conservationist Nancy FitzSimmons of the University of Canberra. Australia, organization and treatment of 492 DNA samples of turtle doves.
"They had already been collected by other researchers working with Nancy in 13 spawning grounds in the Pacific and the Indian Ocean, located in Saudi Arabia, in the Chagos Archipelago, Australia, in Solomon Islands, Seychelles, Iran and Malaysia "says Sarah
In 2015, as a postdoctoral fellow in the Science Without Borders program of the National Council for Scientific and Technological Development (CNPq), she returned to Australia to badyze the data in the laboratory of Professor Simon Ho, of the University of Sydney.
"With these works, we are trying to genetically characterize populations that have never been studied with this approach," says Sarah.
"It is important to understand the migratory routes of turtles, which can be born on a nesting beach in an ocean, but migrate thousands of miles and feed elsewhere."
Among the conclusions include: animals from the Indian Ocean could arrive in areas of food production in Brazil, such as Fernando de Noronha and Atol das Rocas. "We also found that the degree of filopathy of female turtles is variable," he says.
This word, from ancient Greek, means "love of the home" and defines the behavior of certain species of animals in order to always return to specific places to feed or procreate.
It was almost a certainty for sea turtles. The results of Sarah's research, however, reversed this dogma. They showed that there is a genetic mix of maternal lineages with distinct origins and that the separation of populations is more complex than previously thought.
This means that they do not always return and all on the beach where they were born to spawn. Or there would be no new nesting sites.
"This may be the only explanation for the colonization of other places, where they would all be badociated with a single nesting beach, and we know that
Multiple Paternity
More recently, in a pioneering work in Brazil, Sarah has studied the multiple authorship of sea turtles in the country.As males are rarely found because they do not leave the oceans, unlike females during the spawning period, most surveys use samples of them for badyzes on the biology of the species.
"Thus, one way to obtain information about humans is to use the genetic information of females and their respective pups to infer data such as the size of the male population ", explains Sarah.
The data have not yet been published." But the work suggests that the breeding population of turtles with head of turtle (Caretta caretta) on the beach of Povoação, in the district of Linhares, in the state of Espirito Santo, seems to be made up of about two men for every woman, "says Sarah.
"The multiple paternity rate, meanwhile, was about 50%, with a contribution of up to three males per nest." In other words, half of the litters have more than one parent. In other words, half of the females have puppies of three different parents.
Maira Carneiro Proietti, oceanographer at the FURG Oceanographic Institute, began studying sea turtles a year before Sarah in 2004, still in third year of oceanology.
"Júlia Reisser and I have today created a project to study people living in the Arvoredo Marine Biological Reserve in Santa Catarina," he recalls. "We are charmed by these animals and since then we have been fascinated by them and we continue to study them."
Since then, Maira has studied several species from different places.
"In my Ph.D., I did research on turtles along the Brazilian coast, especially in isolated sites such as the São Pedro Archipelago and São Paulo and the National Marine Park. Abrolhos, "he explains.
"In my laboratory, we also study turtle-headed turtles and olive turtles (Lepidochelys olivacea) from the coast of Rio Grande do Sul.The goal is to understand their biology and ecology."
One of Maira's main lines of research involves the genetic characterization of immature populations of several species, with the goal of understanding their diversity and connectivity, as well as those living in other parts of the world. world, to contribute to the preservation of these animals.
Hybrid Turtles
19659018] In addition to verifying and understanding the genetic diversity of populations and places of origin, as well as spawning and feeding, the work resulted in a result surprising.
"We have identified young turtles, still puppies, in the feeding areas along the Brazilian coast, as a result of crosses between different species that breed on the coast," Maira explains.
"Up to now, we have observed animals resulting from hybridization between a comb turtle and a comb head, an olive comb, a green head and a pump and an olive."
According to the researcher, before these revelations, hybrid turtles had been reported in the spawning grounds. She says that young hybrids appear to have characteristic distribution patterns, different from those of adults.
"For example, the results of crossing Cabeçuda with comb turtles were found in greater numbers in Praia do Cbadino, in the extreme south of Brazil, which is a known foraging place. for the first, but where the second is commonly produced, "says Maira.
In general, taking into account all species, not just hybrids, the work of the scientist FURG shows that the origins of marine turtles found on the country's coasts are much more diverse than we thought previously, with high contributions also from West Africa and the Caribbean, besides Trindade Island, Brazil.
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