I won't leave this hanging forever since no one wants it.
There are two wrong implicit assumptions here. Evolution does not assume a snake (or even dinosaur) gave birth to a bird. No saltation. Someone now wants to announce that unctuated equilibrium is a "hopeful monster" theory. No, it isn't. Read here.
Just as importantly, whole groups evolve. Some kind of barrier arises between a sub-population and the rest of the species. It may be a geographical barrier. It may be a habitat preference arising during a period of adaptive radiation. There is no problem within the evolving sub-population finding a compatible mate. Even if the group is evolving "rapidly" on evolutionary timescales, nothing crazy happens in one generation. All through the process, members of the group remain sexually compatible with each other. Because it's a whole subpopulation evolving, compatibility exists within the group even as its members are slowly losing it with other groups.
"Because it's a whole subpopulation evolving, compatibility exists within the group even as its members are slowly losing it with other groups."
Can you give me an example so I can get a more concret idea of exactly how that works?
Thanks.
"Under some circumstances natural selection does play a role in the origin of new species, by which I mean a splitting of one species lineage into two different lineages that do not interbreed with one another -- for example, the splitting of one ancestral primate lineage into one that became today’s chimpanzee and the other that became the hominid line resulting in our own species. The process of splitting and becoming reproductively isolated, that is, incapable of breeding with one another, can often involve natural selection but perhaps not always."
http://www.actionbioscience.org/evolution/futuyma.html
Do you consider this correct?