Wednesday, September 17, 2014

My Year of Darwin 9/17/2014: No idea what is a species is

 Charles Darwin

"By the way I met the other day Phillips, the palaeontologist, & he asked me "how do you define species?" - I answered "I cannot" Whereupon he said "at last I have found out the only true definition, - 'any form which has ever has a specific name"!..."  Charles Darwin, Letter to Asa Gray, November 1857

Yep, species definitions are a bug bear. Variation was still not important enough to taxonomists at the time to give proper insights into species and speciation, the latter of which wasn't widely accepted as actually being a real phenomenon. I still push the evolutionary/phylogenetic species concept - that species are populations that are unique from other populations (that's the diagnostic) and are evolving independently (that's the ontology aspect). Down with the Biological Species Concept!  


  1. So if I follow your argument correctly, you would regard the Guadalupe Junco as a separate species given both uniqueness and independent evolution (regardless of whether they could theoretically interbreed with mainland Juncos) but would regard "Oregon" Juncos and "Slate-Colored" Juncos as members of the same species since gene flow is precluding independent evolution?

  2. True. If two populations can't reproduce then they must be evolving independently. But populations can be evolving independently even if they can still reproduce together - that ability, if species are geographically separate, seems irrelevant.