The Extended Phenotype

from Wikipedia, the free encyclopedia

The Extended Phenotype (with the subtitle The Gene as the Unit of Selection and later The Long Reach of the Gene ) is a popular science non-fiction book published in 1982 by the English evolutionary biologist Richard Dawkins . In 1999 a revised version with an afterword by the philosopher Daniel Dennett was published. The German-language edition appeared in 2010 under the title The extended phenotype : The long arm of the genes . Dawkins regards the concept of the Extended Phenotype as his main contribution to the theory of evolution .

content

Nests are a typical example of the expanded phenotype of living things
3 meter high termite mound in Kenya :
a small animal with a very noticeable extended phenotype

Dawkins expands on the idea, developed in his earlier book The Selfish Gene , that an organism is a "survival machine" constructed from its genes in order to maximize the genes' chances of spreading in the gene pool. In The Extended Phenotype , he treats the subject from a more technical point of view, especially to counter criticism of The Selfish Gene .

In this book, Dawkins formulates his thesis of the Extended Phenotype further. The influence of a gene can only be seen in the context of its competing alleles . (Different alleles of a gene have different effects on the phenotype. For example, different alleles could exist for the color of an animal's coat, and the color would be determined by the allele present in the genome of an animal specimen.) In the classical sense, the phenotype is the sum of all external identifiable characteristics of an individual, but Dawkins wants to describe the sum of all effects of a gene with his definition of the extended phentoype . As examples, Dawkins cites genes that do not change the classic phenotype (with characteristics such as size, hair color or eye color), but rather control the behavior of an organism and its interactions with the environment. Another example would be a gene in a parasite that changes a certain behavior of its host, with which the gene itself gives itself a survival advantage (namely by the host behaving more advantageously for the parasite and allowing it to pass on its genes more - see example at web links ) . Consequently, Dawkins speaks of the “gene for appropriate beaver dams” in the beaver genotype, with a very indirect and long-range effect. Dawkins summarizes his thesis as follows:

"An animal's behavior tends to maximize the survival of the genes 'for' that behavior, whether or not those genes happen to be in the body of the particular animal performing it."

"An animal's behavior tends to maximize the survival of the genes 'for' that behavior, regardless of whether these genes happen to be in the body of the very animal that is doing it."

As with the egoistic gene , Dawkins tries in this book to focus more on the theory of evolution with the individual gene instead of organisms or even species. Because, he argues, ultimately it is the individual gene that succeeds and remains in the gene pool or not, and this can be independent of species and races (this is how certain, very successful genes are found in almost all living organisms).

literature

swell

  1. ^ Richard Dawkins: The Extended Phenotype . Oxford University Press, Oxford 1999, p. 233.

Web links