Extended phenotype
Cover of the first edition
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| Author | Richard Dawkins |
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| Country | United Kingdom |
| Language | English |
| Subject | Evolutionary biology |
| Publisher | Oxford University Press |
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Publication date
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1982 |
| Media type | Print, e-book |
| Pages | 307 pp. |
| ISBN | |
| OCLC | 19921696 |
| 575 20 | |
| LC Class | QH375 .D38 1983 |
| Preceded by | The Selfish Gene |
| Followed by | The Blind Watchmaker |
The Extended Phenotype is a 1982 book by Richard Dawkins, in which Dawkins introduced a biological concept of the same name. The main idea is that phenotype should not be limited to biological processes such as protein biosynthesis or tissue growth, but extended to include all effects that a gene has on its environment, inside or outside the body of the individual organism.
Dawkins considers The Extended Phenotype to be a sequel to The Selfish Gene aimed at professional biologists, and as his principal contribution to evolutionary theory.
In the main portion of the book, Dawkins argues that the only thing that genes control directly is the synthesis of proteins. He points to the arbitrariness of restricting the idea of the phenotype to apply only to the phenotypic expression of an organism's genes in its own body. Dawkins develops this idea by pointing to the effect that a gene may have on an organism's environment through that organism's behaviour.
It is commonly suggested that there are three types of extended phenotypes. The first refers to the capacity of animals to modify their environment using architectural constructions. Dawkins cited as examples caddis houses and beaver dams.
He then goes further to point to first animal morphology and ultimately animal behaviour, which can seem advantageous not to the animal itself, but rather to a parasite which afflicts it. It is "parasite manipulation", which is the capacity of several groups of parasites to modify the host behaviour to increase their own fitness. One famous example of this second type of extended phenotype is the suicidal drowning of crickets infected by hairworm, a behaviour that is essential to the parasite's reproductive cycle. Another example of such behaviour is seen in female mosquitoes carrying malaria parasites. The mosquitoes are significantly more attracted to human breath and odours than uninfected mosquitoes. However, a recent study shows that an immune challenge with heat-killed Escherichia coli can generate the same changes in the behaviour as is seen in infection by Plasmodium yoelii. It raises an unanswered question: to what extent is the alteration of host behaviour due to active manipulation by malaria parasites?
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