A quick survey of life on Earth will usually yield two groups: those that produce their own nutrients and those that must get them from other lifeforms. Plants generally fall into the first category, called autotrophs, while animals and fungi are almost exclusively the second, heterotrophs. But digging deeper reveals a host of organisms that can do both: mixotrophs.

"You'd think an organism that can do both photosynthesis and heterotrophy has hit the metabolic jackpot," remarked Holly Moeller, an assistant professor at UC Santa Barbara. "So it's fascinating to think about what the limits are on that."

Members of the Moeller lab carried out a three-year experiment to see how two strains of mixotrophs would adapt to changes in temperature and light level. The team found that one strain evolved to be less photosynthetic at higher temperatures, which may have implications for the climate. The results also support the idea that natural selection may have a stronger effect on organisms with less flexible characteristics. The findings appear in the journal Global Change Biology.