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
Social groups in male and female prisons in the United States point. This difference is a manifestation of gendered social factors which influence male and female populations within prisons and within larger society. The populations and demographics of male and female inmate populations in the US are very different from one another. These differences factor heavily into theories on prisoner social organization. The most significant difference is in the relative size of male and female populations; in 2014 there were approximately 1,440,000 male and 112,000 female prisoners in the United States. The much larger size of the male prison population causes major differences in the institutions in which male and female