Sexual reproduction generates variation and creates offspring that undergoes natural selection leading to species adaptation to a changing environment. Meiosis, the process during which genetic variation is created, is itself also under the influence of the environment and appears to be highly sensitive to temperature stress. High and low temperatures or sudden temperature shifts during meiosis cause various defects resulting in reduced fertility. In plants, heat stress causes reprogramming of gene expression, alterations in chromosome structure, aberrant organization of the cytoskeleton and defects in cytokinesis. Given the importance of fertility for grain production and the persistence of natural populations, understanding how climate change affects meiosis is vital for the assessment of future food production and biodiversity impacts. This project explores natural variation in temperature sensitivity to identify genetic factors and alleles responsible for defects in male meiosis and reduced fertility in Arabidopsis and rice caused by temperature stress.