How Far Should Humans Go to Help Species Adapt?
“Normally, if you have a predator-prey relationship, the prey doesn’t go extinct because they rely on each other,” Moseby observed. As it was, “the cats and foxes increased into hyper-abundance.” Creatures like the lesser bilby and the desert bandicoot “didn’t have a chance to evolve because it all happened very quickly.”
The hope that motivates Moseby’s work is that given a chance, which is to say more time, species may be able to adapt to introduced predators. The results so far have offered some encouragement, but have also proved difficult to interpret.
In one experiment, Moseby and her colleagues released five cats into a fenced-in paddock with a few hundred greater bilbies and left them there for two years. They then caught some of the surviving bilbies and as well as some bilbies from a “predator-free” paddock and attached radio transmitters to their tails. The two groups of radio-tagged bilbies were transferred to another paddock with more cats. After 40 days, only a quarter of the “naïve” bilbies were still alive. By comparison, two-thirds of the “predator-exposed” bilbies had managed to avoid predation. This showed that the bilbies who’d been exposed to cats had better survival skills. But whether these skills were learned or involved selection for bilbies with more cat-savvy genes was—and remains—unclear.
Meanwhile, bettongs that were exposed to cats for 18 months showed changes in behavior that suggested they’d become more predator-wary; for instance, they approached food that had been left out for them more slowly. Once again, though, it was hard to know what these changes indicated.
“The mechanisms are there, but there’s the question: How fast can it happen?” Moseby said. “People say to me, ‘Oh, this could take a hundred years.’ And I say, ‘Yeah, it could take a hundred years. What else are you doing?’ I might not be alive to see it, but that doesn’t mean that it’s not worth doing.”
Moseby “is the most innovative conservation scientist alive, as far as I’m concerned,” Daniel Blumstein, a professor of ecology and evolutionary biology at the University of California, Los Angeles, who has worked with her on several research papers, told me. “She is just so creative.”
Moseby’s is one of a growing number of conservation projects that proceed from the premise it’s no longer enough to protect species from change. Humans are going to have to intervene to help species change.
More than 1,000 miles northeast of Arid Recovery, at the Australian Institute of Marine Science’s National Sea Simulator, near the city of Townsville, researchers are working to produce corals that can survive warmer temperatures. The effort involves crossing corals from the central part of the Great Barrier Reef, where the water is cooler, with corals from the northern part of the reef, where it’s hotter. The offspring of these crosses are then subjected to heat stress in the labs of the Sea Simulator. The hope is that some of them will prove better able to withstand higher temperatures than either of their parents. As part of this effort, researchers are also subjecting generations of coral symbionts to heat stress, in an attempt to select for hardier varieties. (The symbionts—tiny algae from the genus Symbiodinium—provide corals with much of the food they need to build reefs.) The approach has been dubbed “assisted evolution.”
When I visited the SeaSim, as it’s called, it was coral spawning season and a post-doc named Kate Quigley was in charged of the crosses. “We’re really looking for the best of the best,” she told me.
As with bilbies and bettongs, corals are already under strong selective pressure. As the oceans warm, those that can’t take the heat are dying, while those that can persist. (According to a recent report by Australia’s ARC Centre of Excellence for Coral Reef Studies, over the past 30 years, the Great Barrier Reef has lost half of its coral populations, mainly owing to climate change.) Many scientists are skeptical that humans can really “assist” corals in the process of evolution. They note that during their annual spawning, the corals themselves perform millions upon millions of crosses; if some of the products of these unions are particularly hardy, they’ll go on to produce more corals, and evolve on their own.
