A little while ago my uncle and I were discussing the theory of evolution and the appalling percentage of Americans (I'm Canadian, by the way) who still don't believe in evolution. I had made the claim that even though the theory may very well be incomplete, evolution is a proven phenomenon, which it is. And he made a point that I found interesting, and that was that the theory is indeed incomplete because we still are not able to explain how speciation occurs using the theory. The example he used was that even though humans have been breeding animals like dogs, cats, etc. for thousands of years, and artificially selecting for certain traits that we find appealing for one reason or another, which is effectively what evolution does naturally albeit at a hugely accelerated rate since we are able to specifically breed dog X with dog Y in order to get trait Z, which if left to natural evolution might take thousands or even millions of years to occur.
And that even though we have effectively been carrying out artificial evolution on animals at hugely accelerated rates for thousands of years, we have still been as yet unable to produce any actual new species by doing it (I'm talking about in animals here, not bacteria, as they have slightly different definitions of species). That is to say, for example, even though Chihuahuas and Great Danes look vastly different in every way due to our breeding, they are still technically the same species because they could theoretically interbreed to produce fertile offspring (notwithstanding the fact that it would probably be fatal if the Chihuahua was the female), and we have not yet succeeded in actually producing any new species of dog, as the definition of species stands.
That was just one example of what my uncle was trying to point out, he didn't just base his entire argument on that. He concluded that while the Theory of Evolution is indeed accurate, and I know for a fact that it is, it currently fails to adequately explain how speciation occurs. And I must say, I did find his argument compelling. Can anyone explain if it has any flaws, and if so, what they are?
And just to be perfectly clear, I am trying to better my understanding of Evolution, not pick holes in the theory.