27 June 2014

What'sNEW about HGT |

Convergent evolution is the separate evolution of the same systems or features in unrelated species. The phenomenon, a surprise for standard darwinian theory, is observed in all forms of life. If random mutations supply the raw material for adaptation and evolution, how could there be so many coincidences?

But if genetic programs are very old, and can be preserved even when silent, and can be easily acquired by horizontal gene transfer (HGT), as in cosmic ancestry, convergent evolution is to be expected. Now sixteen biologists, geneticists, biochemists, and specialists in related fields from across the United States have analyzed one example of the phenomenon, epitomized by the electric eel. We think their analysis favors cosmic ancestry. Here is their abstract in full:

Little is known about the genetic basis of convergent traits that originate repeatedly over broad taxonomic scales. The myogenic electric organ has evolved six times in fishes to produce electric fields used in communication, navigation, predation, or defense. We have examined the genomic basis of the convergent anatomical and physiological origins of these organs by assembling the genome of the electric eel (Electrophorus electricus) and sequencing electric organ and skeletal muscle transcriptomes from three lineages that have independently evolved electric organs. Our results indicate that, despite millions of years of evolution and large differences in the morphology of electric organ cells, independent lineages have leveraged similar transcription factors and developmental and cellular pathways in the evolution of electric organs.

We have explored many of the articles for evidence relevant to our thematic question: Where do new genetic programs come from? According to mainstream theory, they originate gradually, following mutation and selection pressure within species. Evidence for these origins should be abundant by now. But, so far, we have found nothing convincing, even among these new articles. Instead, usually, gene origins are simply assumed, as in "...Much of the molecular toolkit for animal development originated in the premetazoan era..." (Alegado and N. King, p 401). But the evidence indicates only that the subject genes, at that early time, already existed. Evidence showing how — or even that — they "originated" is not mentioned.

For another example of an unsupported assumption, Geoffrey I. McFadden writes, "Approximately 2 billion years after cyanobacteria-like organisms had invented photosynthesis..." (p 268). The biological evidence indicates only that photosynthesis must have existed by then, not how — or that, ever — it was invented. Of course, it may have been invented, as McFadden assumes, but where is the evidence for that process?

Meanwhile, several of the articles acknowledge that endosymbiosis and horizontal gene transfer profoundly affect the evolution of eukaryotes. And some authors recognize genetic programs that are apparently much older than they were expected to be. This is progress.

The copyright page promises that the articles in the collection will be online at www.cshperspectives.org. We hope this will allow us to word-search them with our computer, because the book's index is not comprehensive. We welcome any pointers to evidence we may have missed.

Patrick J. Keeling and Eugene V. Koonin, eds., The Origin And Evolution of Eukaryotes, ISBN-10:1621820289, Cold Spring Harbor Laboratory Press, 31 May 2014.

A persistent theme is his status as an independent inventor/scientist, and not an employee of a large industry or university. He agrees that big teams are necessary, but he clearly prefers his independence. (And he distrusts peer-review.) Of course he cares about the environment, but he thinks that a lot of environmentalism is misguided. For example, without nuclear energy, we are left with coal as our main source of electricity.

Lovelock admits that the direst predictions of global warming, including his own, have not come true. For one reason, everyone undervalued the thermal inertia of the oceans — at least a thousand times that of the land and air. But warming in the very long run is inevitable, because heat from the sun is increasing. Earth could become like Venus. To deal with this trend, he recommends air-conditioned cities, leaving the rest of Gaia to respond without our interference. Even more radical, he thinks we might engineer a different life form, perhaps partially (or entirely?) electronic. This scenario is included in his observation that the whole planet evolves, and that this evolution accelerated drastically when the steam engine was invented. Humans are now the most influential participants in the evolution of Gaia.

We welcome any suggestions for how to deal with longterm climate change. We only note that the Gaian climate-management already apparent may emerge from genetic programs that precede the origin of life on Earth. Of course, Lovelock could not endorse that idea without risk of crucifixion. Actually, his gentle story-telling and radicalism seem rather Christ-like.