The Cuban solenodon, a nocturnal, football-sized mammal that resembles a chunky shrew, has an abundance of peculiar qualities. It has a long cartilaginous snout and venomous saliva, which it uses to catch and kill insects and worms. It has terrible eyesight and may be capable of echolocation. The few people who have handled one say that it smells like a goat, and when it is startled it runs on its toes, usually in awkward zigzags that do little to help it avoid capture. Like its cousin the Hispaniolan solenodon, whose snout sits on a ball-and-socket joint, it is an evolutionary curiosity. Most plant and animal species share a history with multiple close relatives—kangaroos with wallabies, eagles with hawks, peach trees with cherry trees, and so on. But the solenodons’ lonely lineage diverged from the rest of the mammals’ back in the Cretaceous period, when the dinosaurs still had more than ten million years left on Earth. In a paper published in this week’s issue of Nature, three researchers argue that the protection of outlier species like the solenodon could have disproportionate—and, to a large extent, untapped—benefits for global biodiversity.
Biodiversity is usually understood in simple numerical terms: more species means more biodiversity. In the United States and abroad, most conservation laws are designed to protect as many species as funding and politics allow. But just as diversity within a human population can be measured by more than skin color, diversity within animal and plant communities can be measured in a number of ways. Some species have a unique evolutionary lineage; others perform unusual or even irreplaceable functions in their ecosystems; and still others, such as the solenodons, are sui generis by almost any metric. Until recently, reconstructing a lineage required painstaking guesswork based on tiny variations in anatomy and appearance. The advent of cheap genetic sequencing, however, changed that. At the same time, the increasing prevalence of digital photography and remote-sensing technologies such as drones, along with the growing enthusiasm for citizen science, means that more humans are watching more species more closely than ever before. “We have this massive decline in biodiversity, but, at the same time, over the past decade, there’s been this explosion of all types of data—so now is really the time to use them,” Laura Pollock, a postdoctoral researcher at Grenoble Alpes University, in France, and the lead author of the Nature paper, told me.
In the study, Pollock and her co-authors assessed the global protections for about fifteen thousand species of birds and mammals. When they looked at how well parks and other conservation areas supported the three types of biodiversity—species numbers, evolutionary history, and ecological function—they found that only about a quarter of all species’ diversity was accounted for, with far smaller percentages of evolutionary and functional diversity. However, they also determined that a small but strategic increase in the size of protected areas—just five per cent worldwide—could triple the amount of bird and mammal diversity protected over all, with most of that land protecting multiple kinds of diversity. Though the Nature analysis is global, Pollock suggested that similar studies could be conducted at smaller scales and used to maximize the amount and kinds of diversity protected in particular places.
Existing conservation areas do include some places that are rich in all measures of diversity (Madagascar) and some species that are unique in several senses (giant pandas), but they largely ignore species such as the Cuban solenodon, which lacks an outsized fan base but is even richer than the giant panda in unusual history and behavior. There’s no worldwide alarm about the Dinagat moonrat, a relative of the hedgehog that occurs only on three Philippine islands; the Amami rabbit, an ancient species restricted to two Japanese islands; the starry owlet-nightjar, a seldom seen native of Papua New Guinea; or the invisible rail of Indonesia, a flightless bird that secrets itself in dense palm swamps. Yet all are among the most distinctive species on Earth. The Zoological Society of London, whose EDGE of Existence program tracks the status of evolutionarily distinct species, reports that, of the hundred most unusual mammal species in the world, two-thirds receive little or no conservation attention.
While this disparity presents an opportunity, it also raises the delicate question of which species get to survive the current extinction crisis. Simply protecting the largest possible number of species has a utilitarian appeal; picking and choosing the most unusual smacks of favoritism, or worse. Walter Jetz, a professor of ecology at Yale and a co-author of the Nature study, pointed out that these oddball species are the inheritors of tens of millions of years’ worth of evolutionary history, not to mention unique ecological functions that, once lost, are almost certainly gone forever. “If I were forced to perform triage, I’d be terribly uncomfortable,” he told me. “But I would not want to lose the one remaining representative of a lineage.”
