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View Diary: Why do whales have hips? (146 comments)

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  •  lateral gene transfer (3+ / 0-)

    Transfer of functional genes between and also among lineages of Archaea and Bacteria appears to be relatively common, although biologists continue to research and debate both the frequency and quantitative contribution of so-called lateral gene transfer (i.e., between separate evolutionary lineages) versus classical Darwinian vertical transfer of genes from one generation of a specific lineage to the descendant lineage (i.e., regular ol' asexual or sexual reproduction).

    I think lateral gene transfer is generally thought to be less common (but not unrecognized) from Archaea and Bacteria to lineages of Eukarya or among lineages of Eukarya (except for closely related and not yet completely distinct species), but this is pretty far from my own areas of expertise. One cool example of lateral gene transfer among Eukarya is a species of aphid that comes in red and green color forms in the same populations.  The gene for one color (I think the red) is demonstrably for a pigment that occurs in that specific group of aphids, but the gene for the other color (I think green) is demonstrably from a type of fungus!  This would be a transfer from one of the former Kingdoms (Fungi) to another (Animalia or Metazoa).

    Many of the structures that are inside the cells of Eukarya, whether single celled organisms like most eukaryote lineages or multicelled like fungi, plants, and animals, were originally free living bacteria that became functional and necessary internal symbionts to an ancestral single celled form, and the symbosis became so intimate that the internal bacteria lost their individual identity.  Examples include the mitochondrion, which shares many genes and structures with alpha proteobacteria, and the chloroplast of plants, which shares many genes and structures with photosynthetic cyanobacteria.  These organelles are the descendants of formerly free living microbes!

    The tree concept works very well as a description of aspects of evolutionary history, but in part thanks to the ongoing genetics revolution in science we are increasingly realizing that it is not an adequate image.  The vine is not bad, but the branches of a vine do not merge back into each other in part or in whole after an initial branch!

    What a complicated web life on Earth has woven!

    •  there is a marine mammal skeleton in rocks (0+ / 0-)

      that appear after a big storm washes the sand away in winter.

      Last time I looked I couldn't find them to swipe, then I thought I'd leave them there, 200-500 lbs each, heh.

      Each vertebrae seems to reinforce the sandstone/mudstone around it, and leaves the blocks more or less intact, with the worn stone showing the bones inside.

      It's not unusual to see these fossil chunks in people's yards out here on the best coast.

      This machine kills Fascists.

      by KenBee on Fri Dec 28, 2012 at 07:12:20 PM PST

      [ Parent ]

    •  and thanks for that comment btw (1+ / 0-)
      Recommended by:
      Fiddler On A Hot Tin Roof

      it's pretty amazing biologically, meta physically I don't know what to make of it...but then, I never did anyway.

      I feel another burning question mark in some church's lawn coming up....

      This machine kills Fascists.

      by KenBee on Fri Dec 28, 2012 at 07:16:48 PM PST

      [ Parent ]

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