F1 hybrid
（重定向自First filial generation）
An F1 hybrid (or filial 1 hybrid) is the first filial generation of offspring of distinctly different parental types. F1 hybrids are used in genetics, and in selective breeding, where it may appear as F1 crossbreed. The term is sometimes written with a subscript, as F1 hybrid. The offspring of distinctly different parental types produce a new, uniform phenotype with a combination of characteristics from the parents. In fish breeding, those parents frequently are two closely related fish species, while in plant and animal genetics the parents usually are two inbred lines. Mules are F1 hybrids between horse and donkey. Today, certain domestic–wild hybrid breeds, such as the Savannah cat, are classified by their filial generation number.