Bob Thanks for the fascinating post on the various polecat species. A question: What are the criteria for deciding if two animals are the same species, separate species or sub-species? I remember in the good old days when the major criterion was the ability to reproduce fertile offspring, but that seemed to combine too many species together. I know with the advent of DNA technology, that has become a major tool. I imagine that researchers from different fields of study may have different criteria, genetic, behavioral, etc. Can you clarify this for us? Linda [Posted in FML issue 4568]