

Frozen sperm provided a much-needed boost in genetic diversity for the species. (AP Photo/Cliff Owen)

In the 1980's, "Scarface" was one of the last living members of his species -- one of 18 black-footed ferrets taken into captivity in an attempt to breed them back up to a sustainable population. Now, years after his death, his sperm has been used to introduce some much-needed genetic diversity to his living kin.

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For a critically endangered species, frozen sperm is truly the gift that keeps on giving. As populations dwindle (often with a lot of help from humans), a species loses its genetic diversity. Fewer parents to pick from means a less successful generation of animals, because inbreeding will gradually weaken the population. Scientists are increasingly relying on throwback sperm, turning long-dead males into new dads to give populations some fresh material to work with.

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The black-footed ferret, a critically endangered species native to North America, is the latest animal to benefit. The critters used to be quite numerous, but their population plummeted due to habitat destruction and food scarcity. In a study published Thursday in the journal Animal Conservation, researchers working as part of a U.S. Fish and Wildlife Service recovery program report successfully using sperm frozen as much as 20 years before to increase the genetic diversity of the small population.

It's not an easy process: Even inseminating a female black-footed ferret with fresh samples is an uphill battle. Because the species only ovulates when the physical act of mating triggers the process, scientists had to develop a hormonal treatment that would jumpstart the release of an egg. Once that was perfected (and resulted in over 100 live births, using recently harvested sperm) they moved on to using samples frozen 10 and 20 years prior.

By going that far back in time -- and carefully choosing females that were minimally related to the dead donor in question -- the scientists were able to effectively introduce new males into the population. Their offspring gave an instant boost to the genetic diversity of the species, making its long-term survival much more likely.

Eight kits have been born thanks to this new project. And many of those frozen-sperm kits have already gone on to produce children and grandchildren of their own without need for insemination.

"Our findings show how important it is to bank sperm and other biomaterials from rare and endangered animal species over time," Paul Marinari, senior curator at the Smithsonian Conservation Biology Institute, said in a statement. "These 'snapshots' of biodiversity could be invaluable to future animal conservation efforts, which is why we must make every effort to collect, store and study these materials now."

Gather ye sperm samples while ye may.

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