The problem is more the definition of the term, rather than availability of adequate data. A lot of biologists (and humans!) grew up thinking that "species" had

The problem is more the definition of the term, rather than availability of adequate data. A lot of biologists (and humans!) grew up thinking that "species" had a clear and obvious definition. One result is that their views are very entrenched and people don't realize that there's even a serious definitional problem at hand affecting a critical area of biology.