A question about evolution...?

>>>>>how does it get passed on?

Did you miss the part about the birds and the bees? Evolution means change in allele frequency in a population over time. A new allele in one individual will become more abundant if that allele leads to higher chance of reproductive success. The next generation will have more individuals with that allele and those offspring that inherited the beneficial trait will make more offspring.....

You're working in steps that are too large. It's a very common misconception. You're right that a mutation that big would have to occur in two individuals simultaneously, who would then have to successfully reproduce... meaning the probability of it happening is essentially zero. In reality, if such a large mutation occurred (and they do happen sometimes), the individual would be unable to reproduce, and that mutation wouldn't be passed on to the next generation.

Actual speciation happens much slower, though, and over hundreds or thousands of generations. Each generation is the same species as their parents, grandparents, great-grandparents and so on. Given time, enough tiny changes can stack up (tiny changes being possible, because you don't need to find an exact genetic match to reproduce) that they are a different species than their great-times-1000-grandparents. Think of it this way - you look somewhat like your parents. They look somewhat like their parents, who look somewhat like their parents, and so on and so forth. Every new generation is obviously the offspring of their parents, and there is a clear family tree, even though you might not look much like your great great great great grandparents.

Speciation is much more pronounced when you have two groups that are isolated from one another. Normally, within a population, there is enough interbreeding that there is a baseline level of genetic similarity. If two populations are isolated from one another, that interbreeding stops, and there is no longer anything binding the two groups together. Once they're no longer connected, the two groups begin to accumulate small - but independent - mutations, until they reach a point where they can no-longer interbreed. At this point, they can be said to be separate species.

Think of it like a game of telephone - you know, the one where you whisper a phrase to someone, who whispers it to the next person in line, and so on, until you're left with a phrase that doesn't even resemble the original. In this case, though, you start the phrase going in two different directions, and the phrase is an entire paragraph. The errors in communication will start out slow, and for the first few repetitions, would still be very close to one another. By the end of the game, though, you'd have two completely separate phrases, even though you'd be able to trace them back to a single original phrase.

Yes, you bring up a very important point. Mutation on its own causes very little change.

However, in conjunction with genetic drift, natural selection, and recombination, a mutation can become more common very rapidly.

Also, speciation rarely occurs instantaneously. What specifically occurs is a subject of debate, but instead it is the process of a single population diverging into two. The populations shift apart rather than jump apart. Mutations that result in genetic isolation and mutations that just result in dramatic changes aren't necessarily the same thing.

For your argument to be a valid criticism, there would have to be a "deadline" on evolution--e.g. either it happens within, say, 100 years or it ain't ever gonna happen. This is of course, incorrect. Your argument does not take into account the facts that 1) evolution occurs at the level of populations, not individuals, and 2) the duration (i.e. huge numbers of generations) over which it occurs are in the realm of "deep time," i.e. scales of time far beyond ordinary human comprehension, which is barely capable of dealing with several 25-year generations, let alone millions upon millions of years. In a huge population, evolving over millions or billions of years, that whittles down your percentage of improbability to the level where it becomes a virtual certainty, as long as that mutation confers some kind of advantage vis a vis reproduction. Also, keep in mind that both partners of the mating pair don't have to have the mutation--only one has to have it. That cuts down the probability of it getting passed on to their progeny from 100% to 50%, but THAT is still a huge probability.

The opposite sex does not have to have the mutation also. Since the male and female are both of the same species, only one needs to have the mutation.

"..how does it get passed on?"

Not to be rude, but you do know how sex works, right? You know what alleles are? Think about this - if a particular genetic structure had to come from both parents, there wouldn't be any men around (or rather, men would be coded for by something other than an unmatched Y chromosome).