Have You Seen How He Jokes And Smiles, Yet Sleeps Like A Child...

Nobody has ever seen a new species evolve.

Speciation is probably fairly rare and in many cases might take centuries. Furthermore, recognising a new species during a formative stage can be difficult, because biologists sometimes disagree about how best to define a species. The most widely used definition, Mayr's Concept, recognises a species as a distinct community of reproductively isolated populations: sets of organisms that normally do not or cannot breed outside their community. In practice, this standard can be difficult to apply to organisms isolated by distance or terrain or to plants (and, of course, fossils don't breed). Biologists therefore usually use organisms physical and behavioral traits as clues to their species membership.

Nevertheless, the scientific literature does contain reports of apparent speciation events in plants, insects and worms. In most of these experiments, researchers subjected organisms to various types of selection for anatomical differences, mating behaviors, habitat preferences and other traits finding that they had created populations of organisms that did not breed with outsiders.