Darwin’s finches story falls apart

“Shaking up the Tree of Life” – http://science.sciencemag.org/content/354/6314/817

Reproductive isolation was, until recently, part of the classic definition of a species. But this definition never worked, first because various species like Neanderthal and Homo Sapiens can mate and birth fertile descendants, and second because this definition left out all nonsexual reproducing organisms.

What is not clear is what should be the definition of “species” and if this concept even makes sense anymore. The debate on the concept of “species” goes on, and some want to retain “reproductive isolation” and add “behavior”, “morphology”, and “environment” to augment the definition. Some are driven by the legal system for conservation that requires clear definition of a specie in order to protect a certain animal (like polar bear) when its “hybrid” cousin is not protected. This is a poor argument as the law should follow nature, not the other way around.

“The tree of life is really a ‘net’ of life” tells us the AAAS paper. Then adding a series of other fuzzy parameters to the old and inadequate definition of a “species” will not revive the “tree of life”. A better alternative is to include more of the same animals into one species. After all, we do not call a human African Pygmy a different species that a Northern European human.

If so, “speciation”, a pillar of Darwinian evolution, might become very rare or even go away as simple “interracial marriage”. ‘Darwin’s finches’ evolution story falls apart, as assigning each one of those finches to a different species turns out to be arbitrarily based on external characteristics. The finches mate with each other easily and the environment adaptation appear reversible once the environment reverts to similar prior conditions.

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