In: Biology
Answer) The Extended Phenotype is a 1982 book by the
evolutionary biologist Richard Dawkins, in which the author
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 suggests that there are three forms of the extended
phenotype. The first is the capacity of animals to modify their
environment using architectural constructions. Dawkins cited as
examples caddis houses and beaver dams.
The second is manipulating other organisms. Dawkins points out that
animal morphology and ultimately animal behavior, may be
advantageous not to the animal itself, but, for instance, to a
parasite which afflicts it – "parasite manipulation". This refers
to the capacity, found in several groups of parasites, to modify
the host behavior 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 behavior that is essential to
the parasite's reproductive cycle.
The third form of the extended phenotype is action at a distance of
the parasite on its host. A common example is the manipulation of
host behavior by cuckoo chicks, which elicit intensive feeding by
the parasitized host birds. These behavioral modifications are not
physically associated with the host but influence the expression of
its behavioral phenotype.
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.