Comments on: The ocean microbe within us

By: Martin

Martin — Thu, 24 Nov 2011 05:23:22 +0000

You say, “SAR11 bacteria also have extremely small genomes–probably because the bacteria were living on a meager food supply and so natural selection favored individual microbes with few genes.”

But wouldn’t a meager food supply favor a large genome, because the organism would have to manufacture many required nutrients. I would think that a small genome would be favored only for organisms living in a nutrient-rich environment, where they could just absorb needed nutrients and wouldn’t need the genes to manufacture them.

By: Dave in Calif

Dave in Calif — Thu, 11 Aug 2011 16:08:47 +0000

Couch potatoes and sun bathers as transitional forms, now that’s funny!

By: David B. Benson

David B. Benson — Sun, 31 Jul 2011 00:20:16 +0000

Matt Gruner — I don’t think there are optima, only local improvements over prior forms.

By: Matt Gruner

Matt Gruner — Sat, 30 Jul 2011 20:42:29 +0000

Presumably the mitochondrial genome is smaller than it was when the first bacteria were endocytosed since a number of genes essential for its function have been moved to the nucleus. The discovery of SAR11 may offer the opportunity to do a rare type of experiment in biology, re-run history and see how it turns out (with some help from molecular biology to speed things along). To what extent does the organization of the mitochondrial (and nuclear) genome represent optimal situations imposed by physical constraints versus neutral changes?

By: hs

hs — Sat, 30 Jul 2011 19:46:54 +0000

Is there supposed to be a link to the actual 60 genome study? Maybe I'm missing it? [CZ: The link is in the post. Here it is again.]

By: This week in science | Hotspyer – Breaking News from around the web

This week in science | Hotspyer – Breaking News from around the web — Sat, 30 Jul 2011 13:24:04 +0000

[...] Zimmer on the ocean microbe within [...]

By: Flower Company » Blog Archive » The ocean microbe within us

Flower Company » Blog Archive » The ocean microbe within us — Sat, 30 Jul 2011 05:40:44 +0000

[...] 28th, 2011 7:58 PM by Carl Zimmer in Evolution, The Tangled Bank, Top posts | 3 comments | RSS feed | [...]

By: G Roelofs

G Roelofs — Sat, 30 Jul 2011 03:39:45 +0000

Is there any chance an early strain of mitochondria might have reversed course and struck off on its own again, ultimately leading to a SAR11-like bacterium rather than the other way around? Two billion years is a very, very long time… However suggestive the present-day similarities are, a whole lot might have transpired to get us here.

[CZ: It's possible, but to make a case for that hypothesis you'd need some evidence--such as showing that all of SAR11 bacteria are more closely related to the mitochondria found in some eukaryotes than others.]

By: amphiox

amphiox — Fri, 29 Jul 2011 19:00:44 +0000

It’s as if alien scientists wanted to figure out where humans came from, but they could only compare us to tulips and E. coli. Our DNA shows we are closer to tulips than E. coli, and so the alien scientists might be tempted to declare that we started out as flowers.

Or perhaps, they’ll conclude that flowers started out like us! (The presence of a second endosymbiotic event in the tulip would support this hypothesis).

They could point to couch potatoes and sunbathers as transitional forms.

By: fer

fer — Fri, 29 Jul 2011 04:34:54 +0000

is amazing how the secondary endosymbiosis has left its signature in the topography of plastid membranes like in dinoflagellates and cryptophytes

By: Rich

Rich — Fri, 29 Jul 2011 02:44:21 +0000

Our DNA shows we are closer to tulips than Giardia, and so the alien scientists might be tempted to declare that we started out as flowers.

I’m not sure that we have resolved the branching order of the eukaryotic supergroups to the level of resolution to make such a distinction.

[CZ: Good point. I'll change it to E. coli]