An interesting article on Evolution News & Views by Wolf-Ekkehard Lönnig, a German molecular plant geneticist. Basically he claims precedence in publishing the process recently re-discovered by Austin L Hughes and published in Heredity. Apparently the idea (called plasticity-relaxation-mutation) has been around in the literature for 25 years, but not in English journals.
Its importance is that it provides an evolutionary adaptive mechanism completely different to (and conceivably a complete replacement for) adaptive natural selection.
Basically the concept is this. An organism has genetic mechanisms capable of dealing with varying environmental situations, presumably by differential expressions of genes. For example, the organism could switch on one set of genes for sweating, etc, in hot weather, and a different set instead if it became cold.
But if the environment stabilises, for example, if it becomes permanently warm, only one set of genes are in use. The other set, now unused, is subject to deleterious mutations (are there any other sort?). As a result, in the course of time the ability to cope with cold weather disappears. An originally multi-potential organism becomes well-adapted, but also less adaptable.
The question raised by Lönnig, who is sympathetic to Intelligent Design, is how the plastic gene-set arises in the first place. Natural selection is a blind, short term process. It cannot adapt organisms to some range of possible future environments. And yet there is evidence across the literature that such plasticity exists.
I’d take the question one step further. At what stage does such multipotentiality appear in the organism? Like mutation generally, PRM is a destructive process. As time goes by, the adaptability of organisms should steadily decrease, and so also their vulnerability to changed circumstances. In the usual common-descent scenario, one would predict a global decline in genetic plasticity, and a trend towards total extinction of life. Yet we actually see a trend towards greater diversity.
Looking in the other direction one would be looking for a last common ancestor with an omnipotential genome – the ultimate front-loading. And if that is not a realistic expectation, at what stage, and by what mechanism, is such plasticity re-injected into the gene line?
This doesn’t look like what Darwin proposed at all.
