Posted by: zyxo | October 27, 2008

Evolution of diversity


NMR structure of the central region of the hum...Image via WikipediaIt is an odd couple : evolution and diversity.
Evolution needs diversity, but diversity is at the mercy of evolution at the same time.

Let me explain.
Evolution does not occur in a homogeneous group. It would be contradictory : “survival of the fittest” when everything or everyone is exactly the same. They are all equally fit.
So there has to be diversity.

But how can diversity evolve ?
In “normal”, stupid living things, like bacteria, lichens, flowers etc. the matter that evolves and has to be diverse is the genetic information : genes, concatenated in long strings of DNA or RNA.
Before these obvious living things there were very elementary organic molecules which also evolved, otherwise they would not have become the real living things. This proto-evolution acted not on genetic information, but on the molecules themselves : they were their own information. There was only one level. The living things as we know them have two levels : i)themselves and ii) their genetic information.
As evolution continued a third level appeared : memes. What we, humans, and possibly, but to a more limited extend the other animals too think, say, communicate. This information also evolves.

This means that the diversity was first diversity of organic molecules, then diversity of genetic information, and now diversity of brain-contained information.

What will be the next level ? Perhaps something link R-memes : information in robots, computors, when it will evolve independently of human command.
We see the beginning of it in artificial intelligent programs .

When these programs will populate the internet, replicate and one way or another will be selected by “the internet” (+ all those that use it) we will see the next level of diversity and evolution.

It is allready partly the case with computer viruses. Only partly, because they still have to be created by people. Beware the day they will mutate, and present themselves each generation as modified viruses, increasing their diversity each minute. The we will have the same problem as with avian flue, but they will be killing computers in stead of people.

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Responses

  1. Yes, the relationship between evolution and diversity is interesting: evolution and life need diversity and mutations, but too much mutations can cause lethal consequences (for instance cancer) in an individual.

    Diversity can be found in every evolutionary system, wherever there is code that can vary. If there is a code, whether genetic, memetic or otherwise, then diversity arises from mutation (insertion, translocation, deletion, duplication, inversion) and recombination (i.e. merging and splitting) as you said earlier.

    Diversity also depends on selection pressure. A recent “New Scientist” (from 27 Sep. 2008) had an article named “As if from nowhere” about the topic of “relaxed selection”, a concept invented by Terry Deacon. Terry Deacon is an anthropology professor at Berkeley. According to Deacon, relaxed selection is a special form of natural selection, where the selection pressure and the competition is low (i.e. where natural selection itself is nearly absent), and the variety of traits which are able to survive and reproduce is high. When the selection pressures lift, genomes go wandering and new, unexpected traits may arise. I think if there is a “relaxed selection”, then one can also speak of a “fierce selection”: a natural selection with fierce competition when the climate is harsh and the food is sparse. Under this conditions only the best, well adapted individuals survive.

    Does natural selection occurs in different degrees? During “relaxed selection”, the system enters an exploration phase: the chances of finding new configurations, traits and features are higher. The selection pressure for a species to remain in the corresponding niche is lower. During “fierce selection”, the system enters an exploitation phase: chances of optimizing existing configurations, traits and features are higher. The selection pressure for a species to remain in the corresponding niche is higher.


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