Microevolution selects only existing variation
From EvoWiki
Contents |
Claim
Microevolution (for example, the development of pesticide resistance) merely selects pre-existing variation. It doesn't demonstrate that mutations create new variation.
Source
Responses
- Selection from pre-existing variations is one aspect of evolution (natural selection). Some mechanisms of evolution decrease variation (e.g., natural selection, sexual selection) whereas other mechanisms increase variation within a gene pool (e.g., mutation, recombination, gene flow).
- The claim, as written, appears to be confusing cause and effect. Microevolution is a result of variations, not the other way around. By definition, a mutation is a new variation in a species' gene pool.
- Many simple experiments demonstrating evolved traits have used bacterial cultures grown asexually from very small populations or even a single cell. Mutation is the only way for the sorts of genetic differences we then observe to arise in these populations.
- add more responses
Fallacies contained in this claim
- Quibbling (X just does Y)
- Slothful Induction (that X does Y is somehow insufficient)
External Links
- Mark Isaak's page for this claim [2]
Further Reading
- Wright, M.C. & Joyce, G.F., 1997. Continuous in-vitro evolution of catalytic function. Science 276: 614-617. See also: Ellington, A.D., Robertson, M.P., & Bull, J., 1997. Ribozymes in wonderland. Science 276: 646-647.
- True, Heather L. and Lindquist, Susan L., 2000 (28 Sep.). A yeast prion provides a mechanism for genetic variation and phenotypic diversity. Nature 407: 477-483. Abstract at [3]
Related claims
- Mutations are rare
- Most mutations are harmful
- Mutations don't add information
- Mutations increase genetic load
- Cost of natural selection is prohibitive (Haldane's dilemma)
- Junk DNA is not really junk
- DNA is the result of intelligence because it contains readable information
