Monday, June 5, 2023

How far should humans go to help species adapt?

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“Normally, if you have a predator-prey relationship, the preys don’t go extinct because they are dependent on each other,” Moseby observed. In fact, “cats and foxes have become a hyper-abundance.” Creatures like the Lesser Bilby and the Desert Bandicoot “haven’t had a chance to evolve because it all happened so quickly.”

The hope that drives Moseby’s work is that, if given a chance, i.e. more time, the species will be able to adapt to introduced predators. The results obtained so far have been encouraging, but have also proved difficult to interpret.

In one experiment, Moseby and his colleagues freed five cats in a fenced pen with a few hundred larger bilbies and left them there for two years. They then grabbed some of the surviving bilbies as well as some bilbies from a “predator-free” enclosure and attached radio transmitters to their tails. The two groups of radiolabelled bilbies were transferred to another pen with more cats. After 40 days, only a quarter of the “naive” bilbies were still alive. By comparison, two-thirds of bilbies “exposed to predators” had successfully avoided predation. This showed that bilbies that had been exposed to cats had better survival skills. But the question of whether these skills were learned or involved the selection of bilbies with genes more familiar to cats was – and remains – uncertain.

Meanwhile, bettongs that were exposed to cats for 18 months showed behavioral changes that suggested they would become more wary of predators; for example, they approached more slowly the food which had been left to them. Once again, however, it was difficult to know what these changes indicated.

“The mechanisms are there, but there is the question: how fast can this happen?” Moseby said. “People say to me, ‘Oh, it could take a hundred years.’ And I’m like, ‘Yeah, it might take a hundred years. What else are you doing? I might not be alive to see it, but that doesn’t mean it’s not worth doing.

Moseby “is the most innovative conservation scientist around, as far as I’m concerned,” Daniel Blumstein, professor of ecology and evolutionary biology at the University of California, Los Angeles, told me, who worked with her. on several research articles. . “She’s so creative.”

Moseby’s is one in a growing number of conservation projects that start from the principle, it is no longer enough to protect species from change. Humans will have to intervene to help change of species.

More than 1,000 miles northeast of Arid Recovery, at the Australian Institute of Marine Sciences’ National Sea Simulator near the town of Townsville, researchers are working to produce corals that can survive warmer temperatures. The effort consists of crossing the corals in the central part of the Great Barrier Reef, where the water is cooler, with corals in the northern part of the reef, where it is warmer. The descendants of these crosses are then subjected to heat stress in the Sea Simulator laboratories. The hope is that some of them will prove to be better able to withstand higher temperatures than either parent. As part of this effort, the researchers are also subjecting generations of coral symbionts to heat stress, in an effort to breed more resistant varieties. (Symbiotes – tiny algae of the genus Symbiodinium—Provide corals with much of the food they need to build reefs.) The approach has been dubbed “evolutionary assistance.”

When I visited the SeaSim, as it’s called, it was coral spawning season and a post-doc named Kate Quigley was in charge of the crosses. “We’re really looking for the best of the best,” she told me.

As with bilbies and bettongs, corals are already subject to strong selective pressure. As the oceans warm, those who can’t stand the heat die, while those who can persist. (According to a recent report from the Australian ARC Center of Excellence for Coral Reef Studies, over the past 30 years, the Great Barrier Reef has lost half of its coral populations, mostly due to climate change.) Many scientists doubt that humans can truly “assist” corals in the process of evolution. They note that during their annual spawning, the corals themselves effect millions upon millions of crosses; if some of the offspring of these unions are particularly hardy, they will continue to produce more corals and evolve on their own.


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