Sexual dimorphism is the condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs. The condition occurs in most animals and some plants. Differences may include secondary sex characteristics, size, weight, color, markings, and may also include behavioral and cognitive differences. These differences may be subtle or exaggerated, and may be subjected to sexual selection and natural selection. The opposite of dimorphism is monomorphism, which is when both biological sexes are phenotypically indistinguishable from each other.