What makes a species?

.The famed AMNH scientist Ernst Mayr proposed the most widely known species definition or concept as ““groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups” By this logic, new species arise when populations are separated across space and time AND some isolating mechanisms evolve such that these separate groups - once members of the same species - can no longer successfully interbreed

As you can imagine this definition does not work in all case (e.g. what about asexual animals?). Heck it barely works for my study animal, the coyote which can breed with wolves in some cases! In fact, many modern day AMNH evolutionary biologists have no love for Mayr’s definition because it’s not always helpful for their work.

Erst Mayer Read a short biography on the man: http://library.mcz.harvard.edu/chronology

Thankfully there is a buffet of species concepts (26 by one author’s count!) for young upstart evolutionary biologists like Sophia and Nancy to chose from ( and to critique)

Sophia and Nancy are wading through the morass of species concepts under the mentorship of herpetologist, David Kizirian, as part of a study to revise the taxonomy of the genus Dinodon, a snake with several species found across Asia. In David’s words, Dinodon’s taxonomy “is a mess.” Within the genus, there are some species that should be 2 and 2 species that should be one. Take for example a 2013 paper co-written by AMNH curator, Dr. Frank Burbink. He discovered that Dinodon was a paraphyletic group. In other words, the Dinodon genus represented a group of species whose members were descended from a common ancestor (good taxonomy) but left out some species who were classified under different genera (bad taxonomy). So Sophia and Nancy will be using morphological traits to see if the taxonomy of Dinodon can be improved. On this quest, the need to define what species concept they are using especially if they stumble across any new, hidden species.

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Monophyletic = Good Poly / Paraphyletic = Bad