The Scientist - Complex genomes evolved by chance

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Discussion Overview

The discussion centers on the evolution of large and complex genomes in multicellular organisms, specifically examining whether this evolution is driven by natural selection or is primarily a result of chance events. The scope includes theoretical perspectives on evolutionary biology and genetic mechanisms.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants reference a paper by Michael Lynch and John Conery, which argues that introns and transposons in eukaryotic genomes are not essential for adaptive diversification but are instead a consequence of reduced population sizes leading to increased random genetic drift.
  • One participant notes that while humans have introns, smaller eukaryotes do not, suggesting that this difference may be due to population size constraints rather than evolutionary advantages.
  • Another participant critiques the assumptions made in the referenced paper, specifically the claim that prokaryotes gave rise to eukaryotes, and questions the classification of bacteria and archaea as prokaryotes, citing newer theories of cell evolution.
  • Concerns are raised about the validity of the paper's conclusions, with one participant expressing skepticism about the details of the arguments presented.
  • There is a mention of the credibility of the journal Science, implying that its peer-review process should lend weight to the published findings.

Areas of Agreement / Disagreement

Participants express differing views on the implications of the paper's arguments, with some supporting the idea of chance-driven evolution while others challenge the foundational assumptions of the paper. The discussion remains unresolved with multiple competing perspectives present.

Contextual Notes

Participants highlight potential limitations in the assumptions made by the authors of the paper, including the classification of prokaryotes and the implications of population size on genetic drift and selection.

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The question of whether the evolution of large and complex genomes in complex multicellular organisms is due to natural selection or simply a function of chance has been the subject of considerable debate. In November 21 Science, Michael Lynch and John Conery at Indiana University argue that the inclusion of intragenic spacers—introns—and transposons, coupled with the increase in gene number associated with genomes of multicellular animals and plants, were not essential for adaptive phenotypic diversification during eukaryotic evolution, but are the result of orders-of-magnitude reductions in population size. This process magnified random genetic drift and prevented “purifying” natural selection from removing them (Science, 302:1401-1404, November 21, 2003).

http://www.biomedcentral.com/news/20031124/03
 
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We have introns, but small eukaryotes do not, not because they are good for us but because our population size is too small for us to stop them accumulating.
Interesting statement..
 
I just read the paper and the were some mistake. First , they assume that prokaryotes gave rise to eucaryotes. They also group bacteria and archea into prokaryotes. These two statements goes against the new theory of cell evolution.

Bacteria and Archeae also exhibit group II introns in their genes
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Abstract&list_uids=1899138
http://www.ncbi.nlm.nih.gov/entrez/...ve&db=PubMed&list_uids=11755525&dopt=Abstract
http://www.blackwell-synergy.com/links/doi/10.1046/j.1462-2920.2003.00398.x/full/

Their idea is interresting but the I am doubtfull about some details
 
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They just published in Science.. you'd think that the journal has a very strict peer reviewing policy..
 

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