Climate change is poised to become a serial killer. With rapid temperature swings around the world, ecosystems have been thrown into flux, exacerbating problems such as habitat loss that have already pushed many plant and animal species to the brink. Some biologists argue that Earth is on the verge of another major extinction event. The big question is whether plants and animals can adapt quickly enough to outpace climate change.
We often think of evolution as something that happens slowly, but that’s not always the case. If the selection pressures are strong enough, evolution can happen over mere decades. For instance, an experiment growing brewer’s yeast in environments with deadly concentrations of salt showed that the microbe population took a hit but then bounced back thanks to rapid changes in a couple genes over just 25 generations.
Identifying genetic adaptations in response to climate change can be tricky. Long-term data sets can tell us the most about whether a species is truly evolving, but it’s hard to tell if any genetic differences were selected for climate reasons alone. What's more, not all genetic adaptations may be beneficial in the long term. And some species may not even need to evolve to survive. Physical or behavioral modifications made during an individual's lifetime may help enough members within a species thrive in a changing world.
Here are 10 species that may already be adapting to climate change—for better or worse:
Corals are highly sensitive to temperature changes in the ocean. Higher temperatures can cause bleaching, when corals spit out the colorful algae that live inside their tissues. Algae give corals nutrients in exchange for shelter, so bleaching can be a death sentence, especially for species in stressful, low-nutrient environments. A 2004 study suggested that coral populations might be shifting to favor corals with algae that are less sensitive to bleaching, but it's unclear if this involves inherited changes in corals’ genes.
However, one species shows how evolution might come to the rescue. According to an April study, table corals (Acropora hyacinthus) can adapt to resist bleaching in warmer waters. On Ofu Island in American Samoa, A. hyacinthus lives in both hot and cool pools. In the lab, researchers tested corals from both environments to see how they reacted to increased heat. They found that only 20 percent of corals from the hot pools bleached, compared to 55 percent from the cool pools. Also, corals from cooler pools that spent a year transplanted in hot pools had an advantage—only 32.5 percent of those corals bleached in the lab tests. The results suggest that the species has the genetic material necessary to adapt and survive the heat, and that heat-tolerant corals might gain a reproductive advantage over time. Some researchers advocate growing heat tolerant corals and planting them in hard hit areas, but such human-assisted evolution garners controversy.