What is a species? A simple question that just about anyone can answer, and yet has been the source of endless debate for decades. Biological diversity just doesn't fit in nice neat little boxes no matter how much we search for a universal species concept. In this episode of the BioAudio podcast Prof. Eryn McFarlane is back to talk about some of the most commonly used definitions of a species, and why they all seem to fail in the end. The diversity of life defies definition.