The Extended Phenotype by Richard Dawkins

“The Extended Phenotype” by Richard Dawkins expands the concept of phenotype to include a gene’s effects on its environment. The book explores gene-centric evolution, the relationship between genotype and phenotype, and the complexities of natural selection.

Genes as the Unit of Selection

  • Dawkins presents the gene-centric view of evolution, where genes are seen as the primary unit of natural selection.
  • The central idea is that the fate of a gene is not solely determined by the survival and reproduction of the organism, but rather by the gene’s success in the gene pool across multiple generations.
  • This includes concepts like ‘selfish genes’ that appear to promote their own survival at the expense of the organism or other genes.

Extended Phenotype

  • Dawkins argues that the effects of a gene are not confined to an organism’s body, but can stretch far into the environment, including the bodies of other organisms.
  • This concept extends the notion of phenotype to include all the environmental effects that a gene has, leading to what Dawkins calls the ‘extended phenotype’.
  • Examples of the extended phenotype could include the construction of beaver dams, bird nests, and spider webs.

Artefact Phenotype

  • An artefact phenotype is any effect of a gene that is not part of the organism’s body but still impacts the organism’s fitness.
  • For instance, the termite mounds, spider webs, beaver dams etc., all constitute artefact phenotypes.

Host Phenotype

  • A host phenotype is an organism whose phenotype is influenced by the genes of another organism.
  • For example, parasites can manipulate their hosts’ behavior to increase their own fitness.

Genes and Behavior

  • Dawkins discusses the role genes play in determining behavior. He suggests that the genes can influence an organism’s behavior, which in turn affects the environment.
  • This extends the concept of phenotype beyond physical traits to also include behavioral traits.

Gene Competition and Cooperation

  • Dawkins explores how genes, even within the same genome, can have conflicting interests and can compete with one another.
  • On the other hand, genes can also cooperate when their interests align, such as in the formation of a body plan.

Outlaw Genes

  • Dawkins introduces the concept of ‘outlaw’ genes, which subvert the normal rules of gene transmission in their favor.
  • These genes can sometimes spread rapidly through populations, even if they don’t confer any benefit to the organism.

Gene’s Eye View

  • Dawkins uses the idea of the ‘gene’s eye view’ to emphasize that it’s the gene’s perspective that matters in evolution, not the organism’s or the species’.
  • This view is a direct consequence of the gene-centric approach to evolution.