[Junior]

If the fossil record is yielding only one individual in several thousand generations (a conservative estimate, considering the time spans we are dealing with), it is going to appear spotty and gappy. Now, for your second contention -- we are dealing with populations, not individuals. If individuals from the separated populations were to be bred, they'd breed fine for several generations after the split. However, as the genes in the two populations grow more and more divergent, the viability of any offspring decreases (horses and mules are sufficiently diverged that any offspring is rendered sterile, but offspring do result). Eventually, the two populations' genes are so divergent that viable offspring are no longer possible. At no point did any of this divergence require two individuals with the same mutation crop up at the same time -- the genes spread through the entire isolated population over time. And over time the mutations in the two separate render the two populations incompatible.

[Aquinasfan]

If the fossil record is yielding only one individual in several thousand generations (a conservative estimate, considering the time spans we are dealing with), it is going to appear spotty and gappy.

So are these mutated individuals significantly and morphologically different from the rest of the group, as the fossil record indicates?

Or is this one-individual-in-several-thousand-generations minutely different from the rest of the herd?

In the former case, the odds of a male and female mutating similarly and simultaneously is effectively zero.

In the latter case, we have the problem of the abscence of transitional forms in the fossil record and the lack of any plausible mechanism for the development of staggeringly complex biological systems.