Tropical Trees Survive Drought by Switching Photosynthesis to Nighttime Operation
Researchers discovered that some tropical trees have evolved to absorb carbon dioxide at night instead of during the day, allowing them to close their pores during hot daytime hours to conserve water during droughts.
Adaptive Photosynthesis Strategy
Some tropical trees have evolved a clever way to survive drought by taking in carbon dioxide at night, allowing them to keep their pores closed during the hot daytime and conserve water. This water-conservation mechanism, known as CAM (Crassulacean Acid Metabolism) photosynthesis, represents a sophisticated evolutionary solution to water stress.
Evolutionary Origins
By comparing three Clusia species, researchers discovered that this water-saving form of photosynthesis, known as CAM, did not arise through a single evolutionary change. Instead, the trait emerged through multiple genetic modifications over millions of years. Ancient genome duplications appear to have provided the raw material for this novel metabolic pathway, allowing the genes necessary for nighttime photosynthesis to evolve alongside the existing daytime machinery.
The CAM Photosynthesis Process
During the night, trees using CAM photosynthesis open their stomata (pores) and absorb CO₂, temporarily storing it in the form of malic acid. During the day, they close their stomata to prevent water loss while the trapped CO₂ is released and fixed into sugars through normal photosynthetic pathways. This decoupling of gas exchange from the driest part of the day confers enormous survival advantages in water-limited environments.
Climate Change Relevance
As global temperatures rise and precipitation patterns shift, understanding how plants adapt to drought stress becomes increasingly important. These tropical trees provide a natural case study of drought adaptation strategies. The research suggests that plants with CAM photosynthesis may be better positioned to survive intensifying dry periods, making them potentially valuable for future agriculture and reforestation efforts in climate-stressed regions.