November 18, 2002
Genetic diversity could be biggest danger to wild turkeys
WEST LAFAYETTE, Ind. If wild turkeys again disappear from most of the countryside, it won't be because they ended up on dining room tables, according to Purdue University researchers.
"The wild turkey was decimated by the 1900s, and although relocation programs created new turkey populations throughout the United States, many lack genetic diversity," said Gene Rhodes, a wildlife geneticist. "This has caused a genetic bottleneck that could ultimately threaten their survival."
Small populations with limited genetic diversity can experience difficulties from inbreeding such as lack of resistance to disease and decreased growth rate, Rhodes said. When reintroducing any species, it's important to capture as much genetic diversity as possible to avoid these pitfalls, he said.
But through the use of DNAbased genetic research, Rhodes and doctoral candidate Emily Latch are using cutting-edge technologies to help relocated wild turkeys survive the problems they face.
Their project is directed toward the development of cost-effective genetic markers that can be used to assess genetic diversity in reintroduced wild turkey populations across North America, Rhodes said.
By examining current genetic diversity in wild turkey populations, the researchers hope to predict viability of the species and create strategies for future wild turkey reintroductions. They expect to be able to apply their conclusions to other relocation programs across the country, not just for turkeys but all wildlife.
The Indiana Wild Turkey reintroduction program was a model for similar programs throughout the United States, Rhodes said, and is the basis for this study. The program has been considered a successful conservation effort.
Indiana's wild turkey population went from zero in the 1940s, when the relocation program began, to nearly 45,000 by 1995, Latch said. Now the numbers are estimated at more than 60,000.
"Most Indiana populations were thought to have been established from a relatively few, closely related donor populations," Latch said. "By the time these new populations visibly show the effects of genetic loss, it may be too late to correct the problem."
The Indiana Department of Natural Resources (IDNR) kept meticulous records about various stocking strategies, which the Purdue researchers found helpful in the design of their genetic sampling schemes. The IDNR also helped in blood sampling and tracking.
Large-scale surveys using DNA-based technologies will enable the researchers to detect genetic differences from very small samples and provide a great deal of data from each individual bird. These surveys will identify wild turkey populations that may have lost genetic diversity and suggest what supplements of genetic stock to introduce before their viability is affected, Latch said.
"The use of DNA-based technologies enables us to detect small-scale genetic differences between individuals and to identify reductions in genetic diversity before they become insurmountable," Latch said.
DNA technologies also allow the researchers to examine the amount of interaction between flocks in localized areas, such as state wildlife management areas, and to predict the potential genetic problems these flocks may be expected to experience, Latch said.
Rhodes said this research will demonstrate to wildlife managers how DNA-based technologies can be used to create stocking strategies that enhance the genetic health of populations.
Their work also demonstrates how fitness is directly affected by the loss of genetic diversity, Latch said.
In the future, this research also may be used to maximize disease resistance in domestic turkeys. As free-range production becomes more prevalent and domestic turkeys are exposed to more types of diseases, it will be important to help predict any potential threats to such an economically important species, she said.
The National Wild Turkey Federation and Purdue University provided funding for this research.
Writer: Maggie Morris
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Source: Gene Rhodes, 494-3601, firstname.lastname@example.org
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