Friday, January 7, 2011

Rank-free classification

We didn't have time to cover this topic on Thursday so I'm going to permit myself a repeat here and introduce it in case any of you want to investigate it further. Good search terms would be Phylogenetic taxonomy or Rank free classification.
You may have heard the saying 'Science progresses by the death of scientists.' Several people have said something like this, perhaps the most famous being Max Planck the German theoretical physicist and generally accepted as the founder of the quantum theory in physics.

A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.

Creating a taxonomy that reflects evolutionary history is now firmly established in biology and the the techniques of cladistics are used to classify organisms into hierarchical taxonomic groups. None of this is very controversial, at least not any more.

However the question of whether we should continue with the Linnean taxonomic code for the naming of the taxa or adopt something different is a very hot topic. I suspect that this is one of those changes that is going to take the death of a generation of biologists to change. There was a good article about the issue in American Scientist in 2006: Attacks on Taxonomy.

Unlike the PhyloCode, Linnean taxonomy does not formally incorporate phylogeny. However, its ranks (species within genus, genus within family, family within class and so on) imply evolutionary relationships. The main drawback of the Linnean system is that groups must be named with suffixes that denote their rank in this hierarchy. For instance, all animal families end in -ae, as in Hominidae. Reclassification of an existing species or discovery of new one can lead to changes in rank and therefore require renaming whole suites of taxonomic groups—a cascade of renaming—even without any new information on those groups. The Phylo-Code solves this problem.

Discover magazine also had a nice article that focused a little more on the people and the controversy: Pushing Phylocode.

“This would be very similar to a set of politicians who decided to bypass the Constitution to create a whole new set of laws.”

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