Samir Okasha is intrigued by a proposed universal law of biology: that complexity inevitably increases in the absence of other evolutionary forces.
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Okasha, S. Does diversity always grow?. Nature 466, 318 (2010). https://doi.org/10.1038/466318a
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DOI: https://doi.org/10.1038/466318a
Jeremy Field
I'm troubled by the thesis that diversity increases most rapidly when selection is weak. The creatures inhabiting the volcanic Galapagos Islands are subject to fierce environmental and presumably selective pressures.
oliver elbs
The title of this review may even be better than the whole book reviewed: If "growth of diversity" is Biology's "First Law", then "Why is there any GROWTH at all?" may be Biology's thermodynamic "Zero Law".
Already Ludwig van Bertalanffy used the last half of his life as a theoretical biologist to study cancer and the related question of "what is GROWTH"?
That question still goes...
Dalius Balciunas
oliver,
you hit the right nail on the head! Namely, zero law of thermodynamics probably can explain why biological complexity in general and biodiversity in particular increase in the course of evolution.
peter borger
"McShea and Brandon do not claim that their law represents a wholly new evolutionary principle, rather that it is a unifying one. The tendency for increasing diversity has been recognized previously in specific situations."
The tendency to generate variation in offspring is a genetic trait. It is not just a blind accumulation of unpredictable mutations, rather the genome is frontloaded with variation-inducing genetic elements (VIGEs). VIGEs are well-known to science. McClintock was the first to identify them in plants: transposons. It appeared they are omnipresent, but they have been mistakenly interpreted as remnants of invasions of ancient retroviruses. Endogenous retrovrisuses qualifiy as VIGEs. TE elements in bacteria, too. The genomes of all organism were frontloaded with genetic elements in order to rapidly generate variation. The generation of increasing diversity is not the first, but rather the second law of biology. The first (unifying) law is: "The tendency to reproduce." (Nothing in biology makes sense, except in the light of reproduction)".
References:
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PB
peter borger
I forgot to mention that RNA viruses, for instance RSV, forms from VIGEs (ERVs) in only two steps by picking up genes from the host.
see: http://creation.com/images/...
The VIGE hypothesis explains the origin of RNA viruses.
NB: In bacteria IS elements qualify as VIGEs (not TE elements as I mentioned above...)
PB