Prokaryotes Ia 053010 - Prokaryotes • Recorded history of...

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Unformatted text preview: Prokaryotes • Recorded history of life began with prokaryotes ~3.5 billion years ago • Prokaryotic unicells alone for ~1 billion years • A persisting “Age of Bacteria” • Dominant creatures on earth – Biochemical diversity – Range of habitats – Resistance to extinction – Biomass Prokaryotes • Metabolic diversity • What are Bacterial Species? • Biofilms • Quorum sensing Metabolic Diversity What are Prokaryotic Species? Traditional: Phenotypic Properties • Ferdinand Cohen • Phenotypic characteristics – Morphology – Metabolism • Phenotypic classifications • Many artificial classifications • Linnaean binomials • Do prokaryotic binomials = prokaryotic “species”?? Do Molecular Cutoffs Lump Species Together? Ward, 2006 The Universal Dynamic Properties of Species • Asexual species : a group whose divergence (genetic variation) is constrained and occasionally rest to zero by intermittent bouts of natural selection • Periodic selection What are Bacterial Species? Fredrick Cohan, Weslyian University • Bacterial taxa called “ecotypes” have the dynamic properties of eukaryotic species • Each currently named bacterial “species” is actually composed of many ecotypes • A currently named prokaryotic species is more like genus than a species • Methods to discover ecotypes Bacteria Form Species Like Everyone Else Ecotype • Set of strains using the same or similar ecologic resources • An adaptive mutant from within the ecotype out-competes to extinction all other strains of the same ecotype • An adaptive mutant does not drive to extinction strains of other ecotypes • Recombination ( horizontal gene transfer ) occurs, but not enough to hinder divergence by periodic selection Periodic Selection Discovery of Ecotypes Through Multilocus Sequence Typing • Partial sequences of 7 “housekeeping protein” gene loci • Strains scored for sequence differences • Strains scored for evolutionary...
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This note was uploaded on 10/09/2010 for the course MCB 3020C taught by Professor Safranek during the Summer '10 term at University of Central Florida.

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Prokaryotes Ia 053010 - Prokaryotes • Recorded history of...

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