RECONSTRUCTING A “UNIVERSAL TREE” Classical view Prokaryotes Eukaryotes 1977: C. Woese 3 “primordial kingdoms” (or domains) - based on ribosomal RNA sequence comparisons All living things share same common ancestor Bacteria Archaea Eucarya Aside: Archaea are not just extremophiles “...the large numbers of environmental rRNA gene sequences...show that [archaea] are present in almost all environments examined...” Robertson Curr Opin Microbiol 2006 University of Illinois Carl Woese (1928- 2012) “… famous for defining the Archaea (a new domain or kingdom of life)”
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RECONSTRUCTING A “UNIVERSAL TREE” Classical view Prokaryotes Eukaryotes 1977: C. Woese 3 “primordial kingdoms” (or domains) - based on ribosomal RNA sequence.
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RECONSTRUCTING A “UNIVERSAL TREE”
Classical view
Prokaryotes Eukaryotes
1977: C. Woese
3 “primordial kingdoms” (or domains)
- based on ribosomal RNA sequence comparisons
All living things share same common ancestor
BacteriaArchaea
Eucarya
Aside: Archaea are not just extremophiles “...the large numbers of environmental rRNA gene sequences...show that [archaea] are present in almost all environments examined...”
Robertson Curr Opin Microbiol 2006
University of IllinoisCarl Woese (1928-2012) “… famous for defining the Archaea (a new domain or kingdom of life)”
1989: Iwabe - rooting the universal tree
- if set of duplicated genes is present in all 3 lineages,
- can use one gene (eg. Gene A2) as an outgroup when comparing the other one (Gene A1) in all 3 lineages
Fig. 5.40
then duplication must have occurred in their common ancestor
Fig. 5.41
- Translational elongation factors EF-G and EF-Tu are homologousand both genes are present in all life forms
… so ancient duplication prior to divergence of 3 superkingdoms
Bacterial lineage diverged prior to archaeal & eukaryotic ones
Plant-animal-fungal trichotomy
Fig. 5.39
Where would you place the root on this tree?
Bacteria
Archaea
Eucarya
Maximum parsimony analysis of – tubulin sequences
“Bootstrap values above 50% are indicated above the nodes … and decay values (additional steps needed to collapse a node) below.”
“…all parsimony and distance-based analyses of four large and diversedata sets support a sister-group relationship between animals and fungi.”
Baldauf & Palmer PNAS 90:11558, 1993
Lane & Archibald Trends Ecol Ecol 23:268, 2008
“Six hypothesized supergroups of eukaryotes”
ENDOSYMBIOTIC ORIGIN OF ORGANELLES
1910 - Mereschkowsky – morphological similarities betweenchloroplasts/mitochondria and bacteria
1960’s - DNA and ribosomes discovered in chloroplasts/mitochondria