Mangroves support coastal ecosystems around the world. In the tropics and subtropics, they rim coastlines and estuaries in thick green bands, providing shelter for everything from monkeys to Bengal tigers to critically endangered sloths. Considering their wide range and unique adaptations to saltwater environments, mangroves seem like an evolutionary success story. But the reality is that mangroves have surprisingly low genetic diversity, which will be a big problem as they attempt to adapt to changing conditions. New research suggests that mangroves may break rather than bend under the stress of the climatic changes to come.
Suhua Shi, an evolutionary biologist at Sun Yat-sen University in Guangzhou, China, and her colleagues surveyed the genetic material of six of the world’s roughly 100 mangrove species, examining 26 populations around the Gulf of Thailand and China’s Hainan Island. The team found that within each species, mangroves are so low in genetic diversity that individual trees are essentially indistinguishable from one another. This means they will have less chance of adapting to a changing world than more diverse species.