Horse outward similarity is an unreliable measure of relatedness. Besides the horse, there are six other species of genus "Equus" in the Equidae family. These are the ass or donkey, "Equus asinus"; the mountain zebra, "Equus zebra"; plains zebra, "Equus quagga"; Grévy's zebra, "Equus grevyi"; the kiang, "Equus kiang"; and the onager, "Equus hemionus". Horses can crossbreed with other members of their genus. The most common hybrid is the mule, a cross between a "jack" (male donkey) and a mare. A related hybrid, a hinny, is a cross between a stallion and a jenny (female donkey). Other hybrids include the zorse,
Multi-male group Multi-male group Multi-male groups, also known as multi-male/multi-female, are a type of social organization where the group contains more than one adult male, more than one adult female, and offspring. Within Order Primates, it is the most common social group type, with group sizes ranging from 10 to 100 individuals. Large groups of primates are called "troops." Examples of species that can be categorized under this type of social organization include many diurnal lemurs, langurs, and most members of the family Cebidae. Multi-male groups, also known as multi-male/multi-female, are a type of social organization in which a group consists of