This site is not maintained. Click here for the new website of Richard Dawkins.

Comment

← Disappearing species

arstood's Avatar Jump to comment 5 by arstood

To prevent the short term effects of inbreeding, like amplification of deleterious recessive alleles, a genetically effective population size of about 50 is needed. To prevent the long term loss of genetic diversity due to drift, a population of about 500 is needed. Genetic diversity allows for rapid evolution as response to a changing environment, and loss of this diversity makes the species unable to adapt quickly. Most mutations are deleterious, and the rare beneficial mutation is not very likely to become fixed in the population simply due to the effects of drift, so relying on mutation, rather than diversity, to increase the ability to adapt is not practical. With random mating, the 34 individuals (which still probably have a genetically effective population size of about 100 or so) would probably become extremely inbred very quickly, but with careful manipulation of mating behavior by humans, it may be possible to keep the genetic diversity at a reasonable level. (genetically effective population size refers to the minimum size of a population that is needed to maintain the same level of diversity. When a population is in rapid decline, the effective population remains higher than the actual population, and when a population rapidly increases, the effective size remains very low.)

Mon, 10 Oct 2011 03:42:50 UTC | #879298