creativspelerr

I would suggest one revision to the original question "Has any experiment been done to create new un-interbreedable species by artificial selection?" "Species" is not based on whether two organisms CAN interbreed but whether they DO interbreed in the wild. A lion and a tiger can be successfully bread even though they are of different species, but in the wild they don't. I think that example is illustrative of two important things: 1) The dividing line between species is fairly fine-grained. If you ask someone to name all the animals they can think of the list might include "squirrels, chipmunks, lions, tigers" but those names tend to be at the genus or even family level. There are a bunch of species of squirrel. 2) Despite that, the definition of a species is still relevant because it is based on the flow or lack of flow of genetic information. A barrier to gene flow determines whether a mutation has the potential to spread throughout the species or bifurcate the species. Gene flow is also a lost less subjective than morphological similarity of difference. Even with the ambiguity around what counts as a species or not (prokaryotic don't conform to that definition very well), I've heard "species" described as the only taxonomic level that is not entirely arbitrary.