
Archaea: The 'Dark Matter' of the Microbial World - sohkamyung
https://www.theatlantic.com/science/archive/2017/03/archaea-sequencing-challenges/518535/?single_page=true
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jessriedel
Is it known why there are no evolutionary intermediates between archea and
eubacteria?

Nick Lane's book _The Vital Questions_ has been highly recommended by the HN
commentariat, and I think it more or less deserves its esteem. Lane gives an
extensive theoretical analysis of the sequence of events wherein a eubacterium
was engulfed by an archea, and the resulting endosymbiosis that was the
beginning of complex (eukaryotic) life.

Apparently, the genomic evidence is strong that the original host was an
archaeon an the original invader (later to become mitochondria) was a
eubacterium. However, I don't think he discusses the origin of this divergence
of eubacteria and archea, and why it persists so cleanly.

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jlarocco
That's something I've always wondered about evolution in general. Why isn't
there a continuum of species? For example, why are there chimpanzees and
humans walking around as discrete species with nothing "in between". Seems
unlikely that a few chimpanzees gave birth to human babies (or I guess some
ancient human ancestor) one day, and then we just branched off and evolved
separately leaving the rest of the chimpanzees behind. Why didn't the "better"
DNA get fed back into the chimpanzee gene pool and the whole species evolve?

Obviously I know nothing about biology, but I'd love a high level explanation.
It's the one thing that's always bothered me about evolution, because nobody
ever explains it, and it seems like magic.

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pygy_
In general, geographic separation leads to speciation. It can be rivers (IIRC
for example bonobos and chimpanzees live on different sides of the Congo
river).

Another interesting example is I think seagulls along the arctic circle that
are split in many species spread along an east-west axis. Most species can
interbreed with their immediate neighbour, but not the neighbour of their
neighbour (except at one point where the extreme populations meet and the
immediate neighbours are not compatible either).

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ihartley
If anyone else is curious, this is called a ring species, and there are only
four known examples:
[https://en.wikipedia.org/wiki/Ring_species](https://en.wikipedia.org/wiki/Ring_species)

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delhanty
>non-breeding, though genetically connected, "end" populations may co-exist in
the same region

This reminds me of the Riemann surface associated with the complex logarithm:

[https://en.wikipedia.org/wiki/Complex_logarithm#The_associat...](https://en.wikipedia.org/wiki/Complex_logarithm#The_associated_Riemann_surface)

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__jal
I love reading about these advances. Not my field, so it is all new to me in a
pop-science way.

And it reaffirms my belief that humans (and all the other species, but I'm
biased) are vastly weirder assemblages than it seems.

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tomcam
Where do the virus and the prion fit into this taxonomy?

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archgoon
They aren't. They're viewed as really weird molecules.

