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.
I’m thinking of a situation where there are subspecies A through (say) H; A can interbreed with B, B with C, etc., and H with A, but no non-adjacent subspecies can produce fertile offspring.
Are there ring species where the first and last populations actually can interbreed? What evolutionary process could feasibly create one?
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.
Wouldn’t that just be a species?
Ourorobos species.
I’m thinking of a situation where there are subspecies A through (say) H; A can interbreed with B, B with C, etc., and H with A, but no non-adjacent subspecies can produce fertile offspring.
A population distributed around a small geographic barrier that grew over time could produce what you want