This type of object could be synchronic, but it is not a tree strucure. A large number of these would make the idea of a "tree of life" invalid. The same think happens in the simpler "ring species" of plants which can occur around mountains. (I heard of these about 50 years ago.) The plants form a circle (a,b,c,d,e,f) where "f" and "a" are ajacent. Variety "a" can interbreed with "b" or f" but not with (c,d,e). Of course were "c" and "d" to die off, there would be two non-interbreeding groups.