> are A and C the same species? To me, they are not. (In my not-know-much about this opinion) And B is a bridge species, or A C adapter species, sort of? But

> are A and C the same species? To me, they are not. (In my not-know-much about this opinion) And B is a bridge species, or A C adapter species, sort of? But is this ABC situation really common? So frequent so motivates how to (not) define what a species is?