Interesting in that in population spread, expanding rings aren't entirely improbable - if a population has a tendency to exhaust resources when it expands into

Interesting in that in population spread, expanding rings aren't entirely improbable - if a population has a tendency to exhaust resources when it expands into an area, its spread could naturally form loops around the edge of depleted, unpopulated areas. It would be interesting if there could be cases where a species expanded like that in the past, and evolved under that kind of closed ring pressure. Even if later that ring broke, how would that ancestry show up in the surviving species' taxonomy?