Prokaryotic Descent

[Theophrastus]

Hey guys,

I'm using a bit of an outdated textbook, so I'ld like a little help on this. What is science's current viewpoint on the structure of the phylogenetic tree for prokaryotes, in terms of what came first, and then with consequent evolutionary changes, what followed? If anyone can give me a good visual, that would be really great (As that's primarily what I'm looking for; I'll discern the rest accordingly). If not, if someone could give me the basic structure, verbally or by means of a link, that would be great. It's for some research I'm doing into the evolution of prokaryote metabolism. Any help would be greatly appreciated

Cheers!

 

ps: If anyone also knows whether certain sections, in terms of chronology, are the topic of dispute, that would also be great to know.

[CharonY]

This is an extremely complicated issue and the info that I assume you are looking for is not actually available. First, bacteria do not leave fossils. So we only got extant species. But even figuring the relationship between those is somewhat a problem as most species definitions simply break down if you want to want to apply them to prokaryotes (and I am not even touching the massive problem of horizontal gene transfer here). The pragmatic view is to use conserved sequence and simply group those closer together than others and at some point draw a species line. What is clear is that bacteria most likely came first. Then at some point archaea split off. The main questions are what the topology after the split looks like. IIRC there are essentially to basic topologies the archaea tree and the eocyte tree. The question there was whether archaea are monophyletic (possess single common ancestor) or paraphyletic. TBH I have not followed the discussion on this.