But, no one has tried to explain to me how macroevolution can happen without Darwin’s survival of the fittest.
That wasn't Darwin's term but you're right in that it is really refering to natural selection (NS). I don't see how anything but drift can occur without some form of selection. Well, perhaps, isolation and drift with no real selection.
The evolutionary process includes, right from day one, natural selection as a major pillor. You don't have "evolution" in the sense it is used in biology without NS.
The term macroevolution comes up again. There isn't really such a separate thing you know. If you have your own definition it might be useful to supply it.
It is, in the way it is occasionally used in biology simply some one or set of "microevolutionary" changes that finally manages to push a population apart into two species. Since species are a bit blurry even that doesn't give a clear split between macro and micro evolution.
Let me try a new way of wording this (just in case it is needed).
There are genetic changes in individual organisms. These are usually very small and most often don't do much or anything. Some of these are large (polypoidy (sp?) for example ). That is all there is as far as changes in the genome go. Large or small these changes may not result in speciation and so they are all "micro" using the biological definition.
The same "size" of changes or even the very same changes might result in a speciation event and then be called "macro".
There is, in biology, nothing else but species. For convenience we group them into larger groups, (genus, family, order etc.) but those are just groups of
species. There is nothing but species!
(as an aside, since the species boundaries can often be a bit blurred we could say that there are only individuals but I think that is a bit extreme)
Anyway, once you have a new species you have macro evolution. Done finished!
Of course, when two species continue to evolve and slit off more species and have more and more time separated from each other the differences between species that was once pretty small can become rather large. It is still just speciation. One after another, changes piled on changes. The changes are all the same kind of changes we called microevolution way back there.
There aren't any macro or micro changes. There are just results that we call speciation or something more.