Immune system study could help conserve endangered species

Sep 16, 2013 by Beth Gavrilles



For decades, scientists have puzzled over what causes the extreme diversity in genes of the immune system, especially for a group of genes known as the , or MHC. These genes are responsible for recognizing and fighting against the many different pathogens and parasites encountered by hosts. MHC genes can harbor enormous variation, even in that have very low diversity in the rest of the genome—particularly species that have experienced population "bottlenecks" caused by catastrophic events that reduce the size of the population and its .



The second hypothesis is that to avoid or to choose a compatible mate drives the variation. The immune genes that detect and fight against parasites also affect traits that make animals—including humans—more or less attractive to potential mates. Studies have shown that that smell different—an indicator they have a different MHC —are more appealing, helping prevent mating between closely related individuals. Animals also might use MHC-based cues to choose partners that will provide "good genes" for their offspring.

To conduct her analysis, Winternitz used MHC genetic sequences for 112 mammal species from GenBank, a repository of genetic data maintained by the National Institutes of Health, and compiled data about those species' behavioral and physical traits from other published databases. She also drew on the Global Mammal Parasite Database compiled by Odum School researchers.


"What the study found, in a nutshell, is that the strength of sexual selection is a much better predictor of MHC immune gene variation than parasitism is," said study co-author Sonia Altizer, an associate professor in the Odum School.

Winternitz added that the findings were "pretty exciting and unexpected," she said. "When I started compiling the data, I had no idea if I would observe any significant associations at all."


"One relevant situation we had in mind was for managers of conservation genetic programs that use fertilizations to maintain a species' standing genetic stock," said Winternitz. "Our results suggest that the current practice of random assignment of mates might be less than optimal for maintaining variability at functionally important immune genes and that employing some opportunity for mate choice could be more effective."

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More information: rspb.royalsocietypublishing.or… /1769/20131605.short

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