“There are a lot of species out there that are overlooked, and when you get to know them, they are just as fascinating and beautiful as the ones we know,” says Gumbs. According to EDGE2 figures, our highest priority mammal should be possum dwarf mountain, a small marsupial that exists in the wild on an area of several square kilometers of the Alps in the Australian state of Victoria. Of the mammal species for which we do not have good conservation data, the most dangerous is the long-eared porcupine, a relative of the hedgehog mainly found in Laos. EDGE ratings have also been calculated for amphibians, birds, corals, reptiles, sharks, rays, and gymnosperms, a group of plants that includes conifers and cycads.
Thinking about animals in terms of their evolutionary differences has become commonplace. The EDGE index is one of the indicators selected for post-2020 global biodiversity framework—a major biodiversity treaty adopted by the United Nations in December 2022. Redlisting Organization of Endangered Species, Alliance Nature Conservancy International, also has a phylogenetic diversity task force, of which Gumbs is vice president. A growing focus, says Gumbs, is on protecting entire ecosystems that preserve many evolutionarily distinct species of plants and animals, rather than focusing on single species.
Of course, evolutionary divergence is just one way to think about conservation priorities. Teams that decide which projects to fund, where to place reserves, and which species to focus on tend to consider many factors before making any major decisions. Rafael Molina Venegas, professor of plant biodiversity at the Universidad Autónoma de Madrid, Spain, says the EDGE2 metric has an interesting twist. If you think of all the species out there as one-of-a-kind books, evolutionary distinct species are like very old, unique books with only a handful of copies. If you lose these rare species, a whole treasure of the world’s evolutionary history will be lost forever.
And there is another reason to care about evolutionary differences. Research by Molina Venegas has found that if we select plant species based on their evolutionary uniqueness, we end up preserving more plant species. useful for humans than if we take a random approach to species selection. In other words, achieving uniqueness seems to be a practical way to think about which species to protect.
One way to think about the EDGE stat is to imagine a fierce battle. A rogue asteroid is one year away from destroying Earth. Fortunately, scientists have identified a completely empty Earth-like planet elsewhere in the Universe. All we have to do is decide which species we want to put on our spacecraft and bring to the new planet. Evolutionary differences may not be a bad starting point, says Molina Venegas. That way, you’ll bring along a variety of creatures, each with a unique function on the new planet. “The hope is that they will complement each other in the new ecosystem that will have to grow there,” he said.
In many ways, humans are waging a fierce slow-motion battle over Earth’s biodiversity. We don’t have to be ready for spaceship just yet, but we do need to think carefully about the tools we have to prevent the loss of irreplaceable species. We have tools like scientific research, gene banks and sanctuaries. The way we think about biodiversity is also an important tool. Everyone wants to save the animals, but we live in a world where species are competing for limited conservation resources and against humanity’s brutal expansion. Unless we make tough decisions about which species to protect, the math won’t match.
