Why can two different species (such as wolves and dogs) breed together, and still be considered different species?
Heather Bird, Rochester United States • If their offspring is fertile then the animals are of the same species; if the offspring is sterile they are of different species. A half-dog half-wolf will always be sterile, as will a mule (half donkey, half horse), but a half-alsatian half-poodle should be fertile. Nigel, Cockfosters UK • According to Steve Jones in his book “Alomst Like a Whale” the international committee which rules on taxonomic problems like this has decided that dogs are really just domesticated wolves that have been artificially bred into funny shapes, and consequently the species designation Canis domesticus (dog) has been formally abolished: they’re just a subspecies of Canis lupus (Wolf). The interesting bit of all this is that there is such a committee. Christopher Young, Sheffield England • The dividing line between species is not always clear-cut, but is usually drawn at the ability to interbreed. Precisely for this reason, the domestic dog and the wolf used to be
