Coral bleaching —caused by the loss of the coral's photosynthetic algae symbiotic partners that live within each polyp—has been linked to global climate change and causes long-term damage to reef ecosystems. The ability of corals to adapt to the effects of global warming is uncertain, but two short papers published this week in Nature claim to provide evidence that corals might be able to evolve their way out of trouble.

In the first study , Andrew Baker of the Wildlife Conservation Society, together with colleagues from Columbia University and the University of Miami, present the results of molecular surveys of coral reefs from around the world, before, during, and after El Niño Southern Oscillation bleaching events, which tend to have warming effects and are thus considered a good model for climate change. Studying the zooxanthellae that give the coral its color, they discovered that one group of symbionts—"clade D"—which is...