Meaning of isolation as it pertains to evolution?

What is the meaning of isolation as it pertains to evolution? And what is one example?Meaning of isolation as it pertains to evolution?
';Isolated'; in that context means genetically isolated - as in not successfully interbreeding. If two populations are isolated from each other, then mutations that become common in one population won't get passed to the other. So each population will evolve in a different direction, and the two may eventually become separate species (if they weren't already). Genetic isolation is required for speciation.Meaning of isolation as it pertains to evolution?
Building on Cirbryn's good answer, there are many examples. My favorite are the scores of species of flightless birds that inhabit (or once inhabited) the Pacific islands. The species were different from each other, and there were often many species on one island filling different ecological niches. But they all started with flying birds that settled on the islands, found them predator-free, and gradually lost the need for flight. The same species of flighted bird could result in different species on different islands.





Of course people hunted the larger flightless birds to extinction, and then introduced rats and mongooses to many of the islands which drove most smaller flightless birds to extinction. So we can't determine the full genetic lineage for many species.