I am starting to hold this belief that evolution is a route to genetic stability:
If you look at simpler living beings (I am currently looking myself at p. falciparum, the cause of the most mortal form of malaria) they tend to genetically evolve very rapidly as genetics is their fundamental way to adapt to new environments. Not only their numbers are so big that mutations can appear in the population more frequently, but also, it is one of the few ways they have to adapt. And of course, their environment might change rather rapidly in very stressful ways (in my study case, with Man bringing in drugs to which p. falciparum seems to adapt very fast… too fast).
More complex beings have other ways to adapt, the most extreme example that I can think of is ourselves (we adapt culturally, linguistically, …) but other “intermediate” forms also have more “degrees of freedom” than just genetics (like a body that can bend, a muscle that can grow larger, …).
Also, in complex beings different parts of the genome are subjected to very different adaptive stresses (think MHC against brain related genes).
We are at an evolutive step (not only biological, but also scientifically and culturally) that genetic evolution (through mutation) is normally a dreadful thing (think cancer).
Therefore I would speculate that evolution tends to breed genetic stability.
As a side note, from this philosophical point I think it is quite easy to guess what I think about things like “molecular clocks” or, in fact, the current underlying assumptions on which phylogenetics is based.
3 Comments to "Evolution is a route to genetic stability"
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Genomic stability that you “see” in humans is just a matter of the timescale you put to it. For “us” the timescale is based on a range of thousands of years, while for the Plasmodium it is a matter of hours.
I understand that in your view an ideal evolutionary accomplishment would be to have a complete and defined set of genes and features, but in reality evolution (or more specifically in this case, natural selection) feeds on the balance between the stability and instability of the genome. The inherent plasticity of each genome is the only way to adapt and evolve.
Genetic evolution is not only mutation and not all mutations are bad. Of course the evolution (or change) by means of mutations in human is obscured by other phenomena such as drift, assortative matings, among others. And for a Plasmodium mutation is not the only way they can evolve and survive. The same factors that drive “ours”, drive theirs. “like a body that can bend, a muscle that can grow larger” which are in most cases defined by the genotype.
You can only fight the environment with the tools the genome has given you.
PS: Os nomes de especies, mesmo as mais conhecidas (E. coli, etc) seguem um padrao de nomenclatura o qual requer que o genero seja escrito iniciando-se com letra maiuscula. Usualmente nomes de especies devem ser em italicos tambem, mas esse e uma norma que pode nao ser respeitada para o caso de algumas especies, e em discussoes mais informais.
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