One of my professors says this often happens with circular island chains; populations from any two adjacent islands can interbreed, but not those from islands farther apart. I don’t have a source. Presumably this doesn’t require an expanding geographic barrier.
One of my professors says this often happens with circular island chains; populations from any two adjacent islands can interbreed, but not those from islands farther apart. I don’t have a source. Presumably this doesn’t require an expanding geographic barrier.