Many animals and plants are losing their genetic diversity, making them more vulnerable

WASHINGTON — Two-thirds of animal and plant populations are declining in genetic diversity, which makes it harder to adapt to environmental changes, according to research published Wednesday.

Long before a species goes extinct, the population becomes smaller and more fragmented, shrinking the number of potential mates and therefore genetic mixing. This leaves a species more vulnerable to future threats such as disease.

''A surprisingly trend was that we saw genetic diversity declining even among" many species that aren't considered at risk, said co-author Catherine Grueber, a conservation biologist at the University of Sydney.

Researchers examined data for 628 species studied between 1985 and 2019. The greatest losses in genetic variation were seen in birds and mammals.

Findings were published in the journal Nature.

''When a species has different genetic solutions, it's better able to deal with changes,'' said David Nogués-Bravo at the University of Copenhagen, who was not involved in the study.

If a new disease spreads through a population or climate change alters summer rainfall, some individuals will fare better than others, in part because of their genes. Higher genetic diversity also means there's a greater chance of a species' survival.

Conservation efforts to connect isolated populations — basically expanding the dating pool for a particular species – can help maintain or even restore genetic diversity.

Florida panthers are an endangered species that have steadily lost habitat to freeways and urban sprawl. By the mid-1990s, the remaining big cats in southern Florida showed clear signs of inbreeding – with kinked tails and low sperm counts in males.

Biologists brought eight female panthers from Texas to Florida. Twenty years later, the number of Florida panthers in the wild has grown significantly and genetic diversity increased.

''Isolated populations suffer,'' said Duke University ecologist Stuart Pimm, who was not part of the research. ''The solution is to reconnect them."

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