Paul Ferraro, a sustainability expert at Johns Hopkins University, described Frank’s report as the “most convincing evidence to date” that declines of wild species can have negative consequences for human health. Yet since there are few species whose erasure would get noticed by more than a handful of conservationists and scientists, this evidence is in danger of being overlooked by most of us, including policy makers.

Bret Hardl, national political director of the Center for Biological Diversity Action Fund, told me that species protections track with politics: Republican administrations tend to be far less supportive than Democratic administrations. “There is a dependable pattern, and Trump was similar to Bush and other Republicans, only worse,” he said. “Trump made a huge push to gut the regulatory structure for all endangered species.”

On Dec. 15, 2020, the Trump administration finalized a regulatory change that shrank protected habitat for wildlife and thereby undermined the Endangered Species Act, the landmark conservation bill signed into law by President Richard M. Nixon in 1973. Those changes came in the wake of an earlier ruling that removed blanket protections for species newly listed as threatened, made it easier to remove species from the endangered list, and allowed the government to disregard the threat of climate change to wildlife. Under these “reforms,” regulators could consider only the economic costs — for example, the anticipated loss of jobs and revenue caused by the prohibition of oil drilling on public lands — when deciding whether a species merited protection. They no longer had to consider the long-term costs of drilling and its effects on human health and well-being.

Conservationists fear that a second Trump administration would go even further. And according to the Trump campaign website, it will.

The campaign promises to rescind every energy- and climate-related regulation put in place by the Biden administration, to open up “vast stores” of oil and gas for extraction on public lands, and to once again remove the United States from the Paris climate agreement.

Meanwhile, among the more frightening and lesser-known proposals of Project 2025, penned by the Heritage Foundation and several people who served in Trump’s first administration, is to fire the “species specialists” at the US Fish and Wildlife Service and abolish the Biological Resources Division of the US Geological Survey.

“If Trump wins, there will be a free-for-all on public lands,” Hardl said. “The damage that would do to wildlife is on a level we have not seen.”

Trump has officially distanced himself from Project 2025. But his campaign spokeswoman Karoline Leavitt did not respond when asked about his specific plans for environmental regulation.

All species are interconnected, and the fate of even the lowliest creature can direct — even determine — the fate of the rest. For example, the American eel is an ancient, well-established creature that few of us think about but upon which many ecosystems rely. As both predators and prey, eels curate waterways, boosting the number of helpful species and reducing the number of invasive species. Without them, rivers become polluted and less welcoming to other creatures, including humans. Once abundant in rivers, lakes, and streams from Maine to the Mississippi, the eel in recent decades has come under siege from dams, overfishing, poaching, and climate change, and the eel population has declined by more than half. And yet because the American eel is listed as threatened but not technically endangered, it is far less likely to be protected under a Trump administration.

Alia Hidayat, an environmental toxicologist and senior policy analyst at the Center for American Progress, is particularly concerned with the future of marine sanctuaries — ocean reserves created to promote biodiversity and protect rare species. “Project 2025 would pause the designation of all new national marine sanctuaries and examine existing ones for potential for drilling and mineral extraction,” she told me. This threatens an area of ocean and freshwater habitat that is more than twice as large as Alaska.

There are thousands of species under threat of extinction, and we can’t save all of them. Nor should we try: Extinction is the engine of evolution. But the World Wildlife Fund estimates that the extinction rate is between 1,000 and 10,000 times higher than it would be were humans not trampling the natural landscapes.

Meanwhile, calculating the value of species protections based on their cost to land developers and extractive industries like oil, gas, and timber is both reductive and dangerous. Rather, we should do whatever we can to save species and habitats through commonsense measures like reducing air and water pollution and limiting our consumption of fossil fuels. For while no single species is essential to human well-being, eliminating a species from an ecosystem is akin to pulling out the bottom rung of a Jenga tower. We do so at our peril.

Ellen Ruppel Shell, a former correspondent for The Atlantic, is author of five books, most recently “Slippery Beast: A True Crime Natural History, With Eels.”