We study how bottlenecks, reductions in the size of populations due to habitat changes or human activities, affect the capacity of plants to tolerate environmental stresses such as temperature extremes, drought, and excess soil salinity. Much of our work examines the capacity of wild relatives of crops such as chickpea and mango to provide improved stress tolerance to crops, or the capacity of rare species to respond to climate change. Our work uses a mixture of field, greenhouse, and laboratory approaches in places such as Turkey, Ethiopia, India, and the Caribbean.