Climate change is outpacing evolution. Scientists are using DNA to catch up

SAN DIEGO (AP) — Evolution works over millennia. Climate change is moving far faster.

That mismatch is killing some of the planet’s most vital ecosystems, from California’s towering redwoods to the seagrass meadows along its coast, both of which store vast amounts of carbon and support complex webs of life.

Marine heat waves, record wildfires and coastal development are pushing these systems beyond their limits as climate change, driven by emissions of fuels like oil and gas, accelerates. An estimated 1 million species face extinction, many within decades, largely due to human activities such as habitat destruction, pollution and overuse of natural resources, according to a 2019 report by a United Nations-affiliated intergovernmental scientific body.

Scientists are working to close the gap with an emerging discipline called conservation genomics: sequencing an organism’s complete genetic blueprint to pinpoint individuals with traits suited to survive drought, disease and other climate extremes, then using that information to guide restoration.

Coral reefs are among the first ecosystems where these genomic tools are being put to use. Repeated marine heat waves, which have caused mass bleaching, have devastated reefs worldwide. By sequencing corals and the algae that live inside them, researchers have identified colonies that naturally withstand higher temperatures and are beginning to test whether selectively breeding and growing those more resilient corals can support reef recovery.

Seagrass are under stress

In Southern California, researchers are applying the approach to eelgrass, a type of seagrass, as traditional restoration methods falter. The plant provides habitat for fish, crabs and plankton, feeds migratory birds and locks away carbon and methane — both heat-trapping greenhouse gases — in coastal sediments.

Conditions in San Diego’s bays are changing. Waters are warming. King tides — the year’s highest tides, which climate change is making more frequent and severe — stir up sediment and reduce the light that reaches the seafloor. Development sends runoff into bays, further clouding the water.

As a result, efforts to replant what’s been lost fail about half the time.

“Conservation genomics is becoming particularly important because right now, the climate is changing — a plant that was growing great in San Diego Bay, now San Diego Bay might be too hot for it,” said Todd Michael, a research professor at the Salk Institute for Biological Studies.

In Mission Bay, Michael and his colleagues discovered a clue to improving those odds: a naturally occurring hybrid eelgrass that outperformed its parent species. The plant, a cross between shallow water eelgrass Zostera marina and deeper water Zostera pacifica, persisted where both parent species struggled.

By sequencing its genome, the team identified genes tied to the plant’s circadian clock that stayed active longer under low light conditions, a pattern scientists believe may help it photosynthesize more efficiently in murky water.

The findings suggest restoration could be improved by selecting or breeding eelgrass better suited to future conditions. But for now, that work remains largely experimental and has not yet been deployed at scale in the field. The researchers have partnered with ecologists at the Scripps Institute of Oceanography to explore how those insights could be applied in future restoration.

Applying similar techniques to Northern California's redwoods

Redwoods are among the tallest and oldest trees on Earth and their forests store more carbon per acre than any other, according to a 2020 study by Save the Redwoods League and Humboldt State University.

While these trees evolved with frequent low intensity fire, today’s hotter and more destructive wildfires, combined with drought, are taking a growing toll. Logging has had an even greater impact: about 95% of old growth redwoods were cut, drastically reducing genetic diversity.

Scientists have already sequenced the redwood genome — a massive undertaking given its size, which is nearly nine times larger than the human genome.

However researchers say the work is not just about restoring what once existed, but preparing forests for a climate that no longer resembles the past.

“Where one organism was adapted to a certain location at one moment in time, it may no longer be,” said David Neale, a forest geneticist and distinguished professor emeritus at the University of California, Davis. “It might require different genetic variation to adapt to the new environment.”

Early analyses have begun to link genes to traits such as drought tolerance and temperature adaptation, but researchers say more rigorous work is needed to confirm those links before they can be used to guide restoration. That work has stalled due to limited funding.

Conservation genomics alone cannot solve climate change

“It can be helpful, but it’s not a solution unto itself,” said Karen Holl, a distinguished professor of environmental studies at the University of California, Santa Cruz. “What should be prioritized is reducing greenhouse gas emissions.”

Genomic tools may help certain species, particularly long-lived ones like redwoods that cannot adapt quickly enough on their own, but they come with limits. Ecosystems are built on complex relationships among plants, animals, microbes and fungi. Engineering or selecting for climate resilient traits in one species does not guarantee the survival of the many others that depend on it.

“Can you genetically engineer a few species that would be more tolerant? Absolutely. But that’s not an ecosystem,” said Holl. “We’re not going to engineer our way out of climate change.”

Follow Annika Hammerschlag on Instagram: @ahammergram.

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