Category Archives: FLE ruminations

Adaptation

Conventional thinking would have us believe that evolution is all about organisms adapting to the environments over time.  Sure, but it probably goes deeper than this. There is no good reason to think that such adaptation is a purely a passive process, as if the environment itself molds organisms like an artist might shape clay.  On the contrary, there is good reason to think organisms play an active role in this process, as if the clay was participating its own shape changes.

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News from the World of Biology

First up, a new clue about the origin of angiosperms:

To Charles Darwin it was an ‘abominable mystery’ and it is a question which has continued to vex evolutionists to this day: when did flowering plants evolve and how did they come to dominate plant life on earth? A new study in Ecology Letters reveals the evolutionary trigger which led to early flowering plants gaining a major competitive advantage over rival species, leading to their subsequent boom and abundance.

The study, by Dr Tim Brodribb and Dr Taylor Field of the University of Tasmania and University of Tennessee, used plant physiology to reveal how flowering plants, including crops, were able to dominate land by evolving more efficient hydraulics, or ‘leaf plumbing’, to increase rates of photosynthesis.

“Flowering plants are the most abundant and ecologically successful group of plants on earth,” said Brodribb. “One reason for this dominance is the relatively high photosynthetic capacity of their leaves, but when and how this increased photosynthetic capacity evolved has been a mystery.”

Using measurements of leaf vein density and a linked hydraulic-photosynthesis model, Brodribb and Field reconstructed the evolution of leaf hydraulic capacity in seed plants. Their results revealed that an evolutionary transformation in the plumbing of angiosperm leaves pushed photosynthetic capacity to new heights.

It will be interesting to track down the molecular machinery involved in the development of this “leaf plumbing,” as front-loading would lead us to expect that it existed prior to the development of angiosperms.

Next up, another example of the way cells facilitate their own evolution:

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More Alu on the Brain

RNA editing, DNA recoding and the evolution of human cognition.

Mattick JS, Mehler MF.

Trends Neurosci. 2008 May;31(5):227-33.

RNA editing appears to be the major mechanism by which environmental signals overwrite encoded genetic information to modify gene function and regulation, particularly in the brain. We suggest that the predominance of Alu elements in the human genome is the result of their evolutionary co-adaptation as a modular substrate for RNA editing, driven by selection for higher-order cognitive function. We show that RNA editing alters transcripts from loci encoding proteins involved in neural cell identity, maturation and function, as well as in DNA repair, implying a role for RNA editing not only in neural transmission and network plasticity but also in brain development, and suggesting that communication of productive changes back to the genome might constitute the molecular basis of long-term memory and higher-order cognition.

FL Thoughts Out Loud

It’s often the case that I get an idea but don’t have the time to write up a decent blog to spell it out.  As a result, some ideas come and go.  So I will start a new tag entitled, FLE ruminations.  Here I will jot down ideas for possible future reference and/or expansion.  We’ll kick it off with some stuff that is in the process of connecting genomic shape to front-loading:

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