Seems many are naive to the controversy about the issue of species, and just accepts Mayr's definition of a biological species.  In  Coyne, J.A.; Orr, H.A. Sinauer Associates; Sunderland, MA: 2004. Speciation  the author describes nine different species concepts. A more recent abstract and article further highlights issues of interest by Mallet (http://journals.royalsociety.org/content/e746161834058h6j/) who adopts a more Darinian view once again. This article (free online) discusses the issues and is a good read: Philos Trans R Soc Lond B Biol Sci. 2008 Sep 27;363(1506):2965-9. Introduction. Speciation in plants and animals: pattern and process.Abbott RJ, Ritchie MG, Hollingsworth PM.