Protecting Future Biodiversity

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Can the Endangered Species Act be used to protect future species?

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The Endangered Species Act (ESA) has saved 98% of species listed as either endangered or threatened. In the face of climate change and predictions of mass species extinctions, can the ESA be used in a forward-looking manner to protect future species that have not yet evolved?

In a 2019 paper, then-law student Natalie Jacewicz argues that the ESA can be interpreted to provide protection for species expected to undergo rapid evolution that would result in a new species.

Congress adopted the ESA in 1973 with bipartisan recognition of the incredible value of biodiversity. When Congress passed the Act, it acknowledged numerous benefits such as “aesthetic, ecological, educational … recreational, and scientific values.”

The way the Act is currently interpreted, responsible agencies must protect three specific categories of fish and wildlife—species, subspecies, and distinct population segments. The category at issue, distinct population segments, was added in an amendment passed in 1978.

Jacewicz explains that the term “distinct population segments” had no meaning in the scientific community and the amendment provided no definition beyond limiting it to vertebrates. Jacewicz argues that this category was added after the original act in 1973 to allow agencies to protect biodiversity at earlier stages of evolution.

Agencies have defined a distinct population segment as a group of a species or subspecies that is discrete from the rest of the species or subspecies. Discrete means the group is either geographically isolated, behaviorally or physically different, or genetically different. The group must also be biologically significant, meaning it represents “an important component in the evolutionary legacy of the species.” Finally, the group must be either endangered or threatened.

Jacewicz argues that this definition should be interpreted to include vulnerable, isolated populations that are not yet “significantly genetically differentiated” but are likely to evolve into such species soon.

Since the passage of the Act, science has advanced to allow scientists to predict which species are likely to evolve in the near future. For example, scientists predicted that when an invasive brown lizard was introduced onto an island, the existing green lizards would adapt to compete. The predictions came true within three years, and the green lizards evolved their behavior and their physical traits.

Jacewicz argues that the ESA should be used to protect groups—such as the original green lizards—that scientists predict will rapidly evolve into a new species. Climate change will likely alter environments and habitats quickly, making such rapid evolution of species more prevalent, Jacewicz explains.

Preserving genetic variation for future biodiversity is one of the main reasons to protect distinct population segments that are likely to evolve, Jacewicz asserts. Humans reap the benefits of biodiversity through medical discoveries, ecological maintenance, and aesthetic enjoyment, Jacewicz states. By protecting the evolution of these groups, future generations will enjoy greater biodiversity, Jacewicz concludes.

The Act itself does not have temporal limits, Jacewicz argues, so applying the Act in a forward-looking manner fits well within the Act’s provisions.

Notably, the Act allows agencies to intervene at early stages of population decline, when a species or subspecies is either endangered or threatened. An endangered species is “any species which is in danger of extinction throughout all or a significant portion of its range.” A threatened species is “any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.”

The Act provides no definition for “foreseeable future” and agencies have interpreted it to extend as long as 100 years. Jacewicz argues that this flexible definition could extend to protect distinct population segments that will likely evolve into new species or subspecies in the near future.

Some critics of the ESA argue that the law is already too cumbersome, though. Critics are concerned with delays and costs for development projects. In a 2017 report, the U.S. Department of the Interior stated that “the time and expense associated with satisfying the interagency consultation requirements are unnecessarily burdensome.” A nature advocacy organization lists 177 reported attempts by some members of the 115th Congress to weaken the ESA.

Supporters of expanding the ESA argue that it is imperative to fight against the effects that climate change will have on species. A legal director at the Natural Resources Defense Council explains that “many parts of the Endangered Species Act could be helpful in taking a more forward-looking perspective on climate impacts to wildlife.”

Jacewicz concedes that applying the ESA to protect species with the potential to become genetically different presents some challenges, but ultimately concludes that they are solvable and should not prevent conservation efforts to preserve potential biodiversity. Jacewicz argues that “the Endangered Species Act was written in a capacious way to generously protect biodiversity” and that it is time to use the Act to protect future biodiversity as well.