Field of Science

So long and thanks for all the Archaea

Can't do any better than this title stolen from a colleagues blog.  For those of us who teach about big patterns in biological diversity, one of the giants, Carl Woese, has died.  His research produced a complete revolution in phylogenetic theory, and he lived long enough to see how important and successful his contribution was.  To explain briefly, the differences between prokaryotes and eukaryotes was long considered to be the great diversity divide.  Organisms either had nuclei and membrane bound organelles (chloroplasts and mitochondria), eukaryotes, or they lacked them, or "came before them", i.e., pro- karyon (= nucleus).  Prokaryotes were more or less synonymous with bacteria, and eukaryotes were all the rest of living organisms.  But Woese's research showed that a group formerly called the Archaebacteria were actually a distinct lineage and that these Archaeans, as they became known (misspelled in this old lecture figure), have a more recent common ancestry with Eukaryotes.  80s ribosomes typical of eukaryotes are twice the size of 70s ribosomes because of two large insertions, one in each of the two ribosome subunits.  Archeans have one of the two insertions, but not the other, thus the relationship diagrammed above.  Prokaryotes used to be called Kingdom Monera or Monerans, but now this taxonomic hypothesis is falsified because it no longer consists of a single evolutionary lineage.   

1 comment:

Jenn said...

Love the title of this post.

And isn't it nice when someone gets to see the changes they made? Seems like it doesn't happen that often, although more in modern times than in historic.