Hybrid (biology) are the mule, a cross between a female horse and a male donkey, and the hinny, a cross between a female donkey and a male horse. Pairs of complementary types like the mule and hinny are called reciprocal hybrids. Among many other mammal crosses are hybrid camels, crosses between a bactrian camel and a dromedary. The first known instance of hybrid speciation in marine mammals was discovered in 2014. The clymene dolphin ("Stenella clymene") is a hybrid of two Atlantic species, the spinner and striped dolphins. Cagebird breeders sometimes breed bird hybrids known as mules between species of finch, such
Gray (horse) will always become gray. If a gray horse is homozygous (GG), meaning that it has a gray allele from both parents, it will always produce gray offspring. However, if a gray horse is heterozygous (Gg), meaning it inherits one copy of the recessive gene (g), that animal may produce offspring who are not gray (depending on what color gene an offspring inherits from its other parent). Conversely, a gray horse must have at least one gray parent. Genetic testing is now possible to determine whether a horse is homozygous or heterozygous for gray, or if it does not carry the