Monitoring the populations of one of nature's slower creatures could become faster, thanks to the University of Georgia.
UGA researchers have developed an easier, more cost effective way to learn more about male marine turtles, a traditionally elusive creature in the world's oceans.
The process allows for researchers to determine genetic information about breeding male turtles from a single egg. As male turtle populations are on the decline, this new technique will enable biologists and other researchers to create an official database of male turtles to better assist in biodiversity and species preservation.
"You could have the collapse of the largest green turtle population in the world because of this lack of male production. Fewer males breeding means less genetic diversity in the next generation of turtles," said Brian Shamblin, lead author of the study and a senior research scientist in the UGA Warnell School of Forestry and Natural Resources. "We want to try to maintain as much genetic diversity as we can. Genetic diversity gives the populations more resiliency. It's kind of an insurance policy for them."
Male turtles don't often return to land, making them hard to study
As male turtles rarely return to land after they hatch, they are difficult to track and observe.
Previously, researchers like Shamblin have relied on satellite tracking or sampling multiple hatchlings and mothers to identify father turtles and to figure out how many males exist. Both of those methods present unique challenges in terms of invasiveness, time and logistics.
Shamblin's new technique uses a single egg from a nest. By isolating a thin membrane inside of an egg, researchers can extract and analyze the DNA from the sperm stuck inside.
Males are mysterious in the sea turtle world and are really important to understand.
Brian Shamblin, Warnell School of Forestry & Natural Resources
"It sort of blows my mind that this technique works as well as it does and as consistently as it does. We can get information about the whole set of eggs from that nest without ever having to interact with the nesting female or interact with any of the hatchlings," he said.
In replicating the process across nests from loggerhead and green turtles in the Southeast and comparing accuracy to hatchling samples, the researchers successfully determined the paternity profiles of breeding males.
This technique allows researchers to determine how many male turtles fathered a nest. As multiple males can father one nest, this process can help researchers analyze how male turtle genetics shift across broad populations.
"The nice thing about this method is that we're getting male and female information out of that one egg, and the technique is something that we can scale up at a population level. Males are mysterious in the sea turtle world and are really important to understand," Shamblin said.
Understanding behaviors of male turtles could help overall species preservation
Warmer sands lead to more female hatchlings. Because of this, over time, the sex ratio of turtle populations can become skewed. Without a greater understanding of male loggerheads and green sea turtles, fewer male offspring could be produced, and males could become a limiting factor.
By establishing a reliable database of breeding male turtle genetics, mating patterns and lineage, researchers will also be able to track the state of the turtle populations on a broad scale.
"Sea turtles are iconic and have been around for millions of years, so they've managed to survive a lot of environmental changes over that time," Shamblin said. "It's up to us to try to figure out what we can do to help them continue to do that. Now that we have the male side of that equation to perfect, we can."
Published in Ecology and Evolution, the study was done in collaboration with Cheryl Sanchez and Simona Ceriani of the Florida Fish and Wildlife Research Institute and Sean Perry, an assistant professor at Midwestern University.
