Originally posted by: SparkyJJO
natural selection != evolution. There is no change of species from one into the other. Minor adaptations? Sure, to a point. But cross-species morphing? No.
Natural selection is a mechanism by which evolution occurs, they are very much related to each other.
To those of you that don't believe in macroevolution, what happens when several "microevolutionary" events occur to a population? 6x COMBO microevolution BONUS!? Evolution is the change in allele frequencies over time. While you can make broad assignments for macro and microevolution, you can't make exact distinctions between the two. Is it macroevolution when allele frequencies for 2 traits change in a population over time? How about 6? Where do you draw the line between your acceptable microevolution and unacceptable macroevolution?
To address your quote denying speciation specifically, different stages of speciation by evolution have been observed many times within just our lifetimes. Here I will gives examples of speciation by the biological species concept, because that is easiest to apply, but the phylogentic species concept works too. Speciation occurs in 3 stages, 1) A barrier to gene exchange seperates 2 populations (be it allopatric or sympatric, ect) 2) Divergence of lineages (by the processes of selection, mutation, and genetic drift) 3) And ultimately, the 2 populations become reproductively incompatible.
1) Barriers to gene flow could be changes in the environment, the migration of a population to a distant island, the development of a new food source. In any case, populations become isolated, I doubt anyone can deny that.
2) Now the populations will diverge. It could be by evolution, even "microevolution", and the isolated populations adapt differently to the environment. But even if you don't believe in evolution, this divergence can still occur. It's called genetic drift or random chance. Simple statistics show that a small isolated population has a high chance of have certain alleles move to fixation by the random changes in inherited allele frequencies over time. Or mutations will introduce new alleles into the population, mutations are well documented occurrences.
3) Now it is natural to see, that after undergoing changes seen in 2), the 2 isolated populations, if they are ever brought together again, may no longer mate with each other. Perhaps their mating song changed by one note simply due to random chance. Perhaps one population developed protective spines, changing their appearance so that the other population is no longer attracted to it. Whatever the reason, speciation has now occured. This is an example of macroevolution.
People need to understand, evolution is the unifying theory of biology. Every process in biology can be explained in the context of evolution.
Anyways, I suggest to the OP to specifically read a textbook on evolutionary biology. I used Evolutionary Analysis by Scott Freeman and Jon C. Herron, and while it's not the msot exciting book, it presents a good amount of evidence and case studies detailing evolutionary processes, both macro and micro.