The diverse patterns on the diamondback terrapins’ intricately grooved shell may be their claim to fame, but a newly published U.S. Geological Survey study of the genetic variation underneath their shell holds one key to rescuing these coastal turtles.
Listed as an endangered species in Rhode Island and deemed threatened in Massachusetts, the terrapin is the only turtle in North America that spends its entire life in coastal marshes and mangroves. Seven different subspecies of terrapins are currently recognized by scientists based on external traits, such as their skin color and the shape of their shells. Each subspecies occupies a strip of the eastern seaboard or Gulf of Mexico coastline, from as far north as Massachusetts to as far west as Texas.
Many of the coastal states where terrapins are found have designated it a species of special concern, and the states are looking to address the issues the terrapins face due to fragmentation of their coastal habitats. An increasingly patchy swath of isolated coastal marshes makes it harder for terrapins to find each other and continue interbreeding as they have in the past.
“Before now, it was not clear how terrapin genetics varied across the range,” said Kristen Hart, a USGS research ecologist and lead author of the study. “Understanding this variation across the landscape helps land managers develop conservation plans. For example, they may pinpoint areas where habitat protection can be supplemented with migration corridors.”
Agencies often maintain migration corridors to help wildlife continue to breed based on their historic patterns. These are areas where habitat restoration, regulatory policies, or other means are used to ensure animals can pass safely between two or more prime areas of habitat. Well-placed corridors could maintain the terrapins’ existing natural diversity and keep their overall population numbers robust, explained Hart.
“Diversity loss can be a silent threat to many species,” explained Maggie Hunter, a USGS research geneticist and co-author of the study. “The threat to long-term survival of terrapins occurs if they become separated into isolated groups. Isolation can affect their overall survival several generations down the line.”
To support a healthy mix of genetic diversity, however, managers must first understand the existing genetic variation.
“Healthy interbreeding doesn’t mean that turtles from Maine have to interbreed with those from Texas,” explained Hunter. “Once managers know where ‘natural breaks’ in populations occur, they can focus on keeping terrapin populations healthy by enabling reproduction within each of those distinct groups.”
To identify those natural genetic breaks, Hart teamed up with Hunter and USGS research geneticist Tim King to study their breeding patterns using DNA from the blood samples of nearly a thousand terrapins. Based on their variation in 12 genetic markers -- strands of DNA that King had decoded for comparative purposes -- the terrapins were assigned into genetically similar groups.
They found only 4 genetically distinct populations, which came as a surprise, given there are 7 recognized terrapin subspecies. This means the ‘natural breaks’ in breeding don’t correspond to the ranges of those subspecies.
The results of the genetic study offer one more benefit. During the 1920s, terrapins were considered a delicacy and hunted for their meat, and they still occasionally turn up as food in markets around the country. Now, wildlife agencies can use a DNA test to determine where these turtles came from, so they can return rescued turtles back to their original habitat.
The study, “Regional differentiation among populations of the Diamondback terrapin (Malaclemys terrapin)” was recently published in the journal Conservation Genetics.
Rachel Pawlitz | Eurek Alert!
Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF
Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Life Sciences
18.07.2018 | Materials Sciences
18.07.2018 | Health and Medicine