If the apple maggot flies preference for the apple is decreased so much that it has equal preference between the two trees, then the incipient species will begin to interbreed. This is because there is now no reason for them to not mate, the previous prezygotic barrier is now abolished. They are able to mate freely resulting with a viable offspring and no natural selectiuon against them. They will no longer remain separated, they will over time either grow into one species as they continue to interbreed, or another barrier will be formed through mutation or a behavoirial change and reinforced. This allows for the separtion back into the two trees they prefer.
Comments
Nice paragraph. However there
Nice paragraph. However there are some grammatical errors that should be fixed. For example, the first sentence wait the "the prefernce for the apple is decreased so much" which sounds a bit awkward!
Overall it's a nice paragraph
Overall it's a nice paragraph with only a few grammatical issues. It is also very short so I would conisder adding some more details or facts