Well, it depends on whether they can produce viable offspring or not. This question gets complicated when one considers species that reproduce asexually, so let's keep our discussion to sexually dimorphic species. Donkeys and horses cannot produce offspring that are able to reproduce, therefore mules are a hybrid species. Donkeys and horses are not the same species.
But if you reject the traditional way of defining species, what definition of "species" would you propose instead?
Yeah I don't think hybridization between species makes them the same species.
Well, it depends on whether they can produce viable offspring or not. This question gets complicated when one considers species that reproduce asexually, so let's keep our discussion to sexually dimorphic species. Donkeys and horses cannot produce offspring that are able to reproduce, therefore mules are a hybrid species. Donkeys and horses are not the same species.
But if you reject the traditional way of defining species, what definition of "species" would you propose instead?