Easier variation
The theory of facilitated variation (ger .: Theory of Facilitated Variation ) is an explanatory model that is designed to complement the theory of evolution understands and with the nature of the variation in the evolution is concerned.
This theory was published in 2005 by Marc Kirschner , founder and chairman of the Systems Biology department at Harvard Medical School , and John Gerhart , professor at the University of California, Berkeley , in their book " The Plausibility of Life " (German title: Die Solution to Darwin's dilemma ).
Summary
You first start the finding that not everything is subject to change in the course of evolution, but a number " conserved core processes " ( conserved core processes are), such as the basic information processing of DNA , RNA and protein biosynthesis . Furthermore, the molecular biological processes that are relevant for the dependence of the phenotypic on the genotypic variation are considered. Three aspects are highlighted that facilitate evolvability and the creation of something new:
- Weak regulatory linkage : This is a form of regulation that can be easily developed and modified in order to couple the conserved core processes with one another in a different configuration. The regulatory signal provides little information, the recipient himself is "maximally informed", i. H. the signal simply selects one of the intended responses from the recipient. This is also known as the permissive interaction .
- Exploratory behavior ( exploratory behavior ): This is the adaptive behavior of certain cellular and developmental core processes that work roughly on the principle of " trial and error " and in this way can generate a large number of specific states, each of which is physiological Interactions can be selectively stabilized. An example of this are microtubules that make contact with the chromosomes during mitosis .
- Compartmentalization: The development of the body plan in animals begins with the phylotypic stage during embryonic development , during which the spatially defined expression of selector genes and, as a result, the secretion of signal proteins takes place for the first time. This “invisible anatomy” itself is preserved for every animal strain, but in connection with the weak regulatory coupling requires independent reaction spaces in the body and thus enables a high adaptability of the visible anatomy.
See also
literature
- Marc W. Kirschner , John C. Gerhart: The Solution to Darwin's Dilemma. How evolution creates complex life. Rowohlt Taschenbuch Verlag, Reinbek near Hamburg 2007, ISBN 978-3-499-62237-3 .