Evolution factor

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In biology , evolution factors are processes through which the gene pool - that is, the totality of all gene variations in a population - is changed. The term is defined by population genetics : evolution factors are processes that lead to changes in the allele frequencies in the gene pool of a population. According to the synthetic theory of evolution , these processes are the cause of all evolutionary changes.

The main evolutionary factors are mutation , recombination , selection and genetic drift .

  • By mutations , spontaneous changes of the base sequences of DNA , produces new genetic material. If a mutation takes place in a cell from which germ cells later emerge, the changed genetic makeup is transferred to the offspring via the fertilized egg cell and thus changes the population's gene pool. The new hereditary disposition leads to characteristics that have not previously occurred in the population. Whether there is a lasting change in the gene pool depends crucially on how the selection affects the new characteristic expression. Hereditary factors that lead to disadvantageous traits either disappear from the gene pool or remain rare.
  • Through recombination , which occurs through meiosis during germ cell formation and nuclear fusion during fertilization, the parents' genes are recombined so that offspring with individual (unique) combinations of genes are created. In the case of recombination, the relative abundances of the genetic makeup in a population remain unchanged, but the variability (especially phenotypic ) of the individuals in a population is effectively increased. Recombination does not take place in asexual reproduction.
  • The selection is the natural selection by the environment. The prerequisite for selection is the variability in a population caused by recombination and mutation. In all populations, more offspring are produced than will later reproduce. Individuals with disadvantageous characteristics have fewer offspring than individuals with more advantageous characteristics. The individuals thus make a different contribution to the gene pool of the next generation due to their characteristics. As a result, the relative frequencies of genetic traits with favorable traits in the population increase, while the relative frequencies of genetic traits with unfavorable traits decrease.
  • Under genetic drift is defined as a random change in the gene pool. It is more effective in small populations than in large ones. In the event of a natural disaster or epidemic, for example, a group of carriers of certain characteristics can suddenly become extinct. The surviving part of the population with a slightly different genetic composition spreads; if individuals with disadvantageous hereditary factors happen to survive, these even spread. Another example of genetic drift is the colonization of a new habitat by a small founder population . The new population shows the frequency distribution of the genetic makeup of the founder population, which by chance differs from that of the parent population.

Evolution factors in the broader sense are also

Web links

Wiktionary: Evolution factor  - explanations of meanings, word origins, synonyms, translations

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  • Herder Lexicon of Biology . Spectrum Academic Publishing House, ISBN 3-86025-156-2
  • Campbell, NA: Biology . Spectrum Academic Publishing House.