How can geographic isolation change a population's gene pool?

evolutionHow can geographic isolation change a population's gene pool?
By itself it doesn't.





If a sub-population of a larger group of organisms is isolated from the main group of that organism, then it will have a subset of the whole gene pool. Maybe it happens to have slightly more of the individuals who have longer horns, for example.


So, this isolated sub-population has - on average - longer horns than the species as a whole.





If the isolation continues for long enough, then random mutations will introduce more variants of the gene pool - and (because mutation is entirely random) these will be different from the mutants appearing in the rest of the population. So maybe, in addition to having longer horns, this sub-population starts to get more individuals with a darker coat colouration too. This is ';genetic drift';.





Finally, the environment that this sub-population is in will probably have slightly different selective pressures than the environment of the rest of the species. Maybe the trees are slightly taller, meaning that individuals with longer necks have an advantage when grazing on foliage. This will result in the sub-population evolving longer necks (or possible the ability to climb trees, or some other adaptation).





Of course, the main population will also have been evolving too, and maybe *they* have evolved sharper eyesight and faster running due to more predators.





So, after a few thousand years of isolation, and after hundreds of generations, the sub-population will be noticeably different from the main species: they'll have longer horns, darker coats, and longer necks, and they'll be a bit slower and have less sharp eyesight too.How can geographic isolation change a population's gene pool?
It just makes it less diverse,wich usually leeds to lower tolerances to many types of diseases. The more diverse a gene pool is, the better(and faster) people can adapt, since you are carrying a wider array of immunities in your gene pool.


Think of it like this:mom's dna+dads=you... now if mom and dads dna are almost the same,you really are only getting half of what a diverse pool would give you. (this is why racists are complete idiots!!)lol.
in breeding.