What, If Anything, Is a Species?

Abstract

Each generation, evolutionary biologists seem doomed to grapple with the ``species question'' epitomized in my title. The task is often seen as Sisyphean, with no final consensus on what really constitutes a ``species'' ever emerging. In contrast, I believe that important strides in understanding what species may or may not be have been taken in the last 50 years, including much important work underway at the present. In particular, we have hope, if not for consensus, at least for a detailed understanding of why consensus on the nature of species has persistently eluded evolutionary biologists.