Can a cat and a rat breed successfully?
Absolutely not. For one thing, you could never persuade the two to mate naturally – a cat would kill a rat rather than mate with it – but even supposing you mixed the sperm and egg in a test-tube, the two simply wouldn’t combine to make a viable embryo. In order for two different species to interbreed, they must be closely related. Generally, species within the same genus can breed – for example, that most famous of hybrids, the mule, is the offspring of a male donkey and female horse, both of which belong to the genus Equus (the offspring of a male horse and female donkey is called a hinny). Depending on how closely related they are, animals in different genera but the same family can sometimes breed – for example, the puma and the leopard both belong to the family Felidae, but the genera Puma and Panthera respectively, and they can interbreed to produce a hybrid called a pumapard. Being closely related basically means that the two species shared an ancestor with each other more recen
