I might be wrong here - I’m not a scientist - but I believe that “natural selection” and “interspecies evolution” are not synonomous. I understand that natural selection has been proved many times over in intraspecies breeing. However, I don’t think there’s been any documented evidence of interspecies evolution. Perhaps the aviatrix (?!) thing but I haven’t seen that in documentation recently.
Given the vast time frame needed for life to form or species to evolve, how could lab experiments ever simulate the actual events?
New species of plants arise all the time and it has been observed both in nature and in the lab. New species of fruit flies have arisen in the laboratory setting that cannot reproduce with the ancestral strain.
However I fully expect you to move the goal posts from ‘Evolution cannot be shown in the lab’ to ‘evolution CAN be shown in the lab,but not speciation’ to a NEW location ‘it is STILL a fruit fly isn't it?’.