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
- Some groups that we classify as species are able to breed together, because they're physically able to get together and genetically similar enough to produce a viable egg. The 'biological species concept' says that two animals are of separate species if they are not able to breed together to produce a fertile hybrid. However, in practice, some closely related groups that we consider to be individual species are prevented from breeding with one another through geographical or other isolation rather than through physical constraints. Given sufficient time in isolation, these groups would be likely to become genetically incompatible with another.
Flit, Leeds UK
- Nigel is wrong. A wolf/dog hybrid is fertile and is in fact not a hybrid at all because wolves and dogs are exactly the same species. The dog is now known scientifically as Canis Lupus Familiaris and not just Canis Familiaris (as it is in older textbooks) in recognition of this fact.
Susan Deal, Sheffield UK
- Definition of a species is more complex than whether it can interbreed. Some same species cannot (maybe geographical change), some different species can and there are reasons for this anomaly but I am not sure why. Ask a taxonomist, but understand that as many opinions as experts.
Steve, Leeds, England
