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The Importance of Diversity to an Animal's Survival

To better understand endangered species, study their genetics.
The Galápagos tortoise feeding on Santa Cruz Island. (Photo: Charlesjsharp/Wikimedia Commons)

The Galápagos tortoise feeding on Santa Cruz Island. (Photo: Charlesjsharp/Wikimedia Commons)

Bad news: There are probably more animals primed for the Endangered Species list than we might think.

According to a study published in the forthcoming November issue of Biological Conservation, wildlife conservationists could do a much better job of tracking endangered or threatened species if they started paying more attention to genetic diversity—not just population loss.

Some threatened species aren't very genetically diverse, due in part to factors like inbreeding and the butterfly effect of global warming. Pollution and habitat degradation can lead to population loss, which can also shrink and muck up an animal's gene pool. Species with lower genetic diversities are becoming increasingly less suited to adapt to factors such as climbing temperatures, emerging diseases, and other effects of climate change.

"If genetic diversity is low, the adaptive potential of a species is compromised."

Using genetic datasets from more than 5,000 studies and nearly 18,000 loci— the positioning of a gene on a chromosome—a research team led by Purdue University's Janna Willoughby analyzed the genetic diversity levels of wild populations of birds, fish, reptiles, amphibians, and mammals. The researchers then used the data to develop a statistical model that might help conservationists to estimate how many generations are left in a population before their gene pool becomes too limited to guarantee long-term survival.

"Understanding these patterns of loss of diversity are important for conservation because the capacity for future evolution is based, at least in part, on the depth of the gene pool," the researchers write. "If genetic diversity is low, the adaptive potential of a species is compromised. Therefore, the maintenance of genetic diversity is often important for the successful conservation of threatened and endangered species."

Willoughby and her team also took a closer look at the Red List—one of the most extensive databases of threatened animals in the world, compiled by the International Union for Conservation of Nature. The database, which ranks species according to how close they are to extinction, doesn't account for genetic diversity, they found—a sign that there could be more threatened species than previously thought. If conservationists don't start studying genetic diversity, Willoughby and her colleagues argue, the potential to overlook species as threatened or endangered could actually be quite high.

"[W]e found that the existing criteria failed to systematically identify populations with low genetic diversity," the researchers write. "To rectify this, we suggest a novel approach for identifying species of conservation need by estimating the expected loss of genetic diversity."

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