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Biology 2nd Baccalaureate

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4.5.2. Natural selection

Natural selection

The natural selection is the process by which the best genetic characteristics of individuals in a population to the environmental conditions of the place where they develop are selected.

Those combinations of genes that determine characteristics that are detrimental because they provide a worse adaptation to the environment of the individual who carries them, will tend to disappear. The individual will have more trouble surviving and leaving offspring with those genes. On the other hand, if you are well adapted to the environment, you will have a better chance of surviving and reproducing, and that your children may have the gene that gives them that advantageous situation over others.

In a very summarized way, it could be said that natural selection has the following phases:

  • Existence of diversity of characters in a population.
  • Differential reproduction. As resources are limited, those better adapted reproduce better than those not adapted to environmental conditions.
  • Inheritance of advantageous characters to descendants.
  • The advantageous character becomes more and more frequent in the population. If the process continues, in the end, all individuals in the population will have that advantageous character.

Humans perform artificial selection is very similar to natural selection. We (the environment) select those plants and animals with the best characteristics (for food, for their beauty, docility, etc.) and we make them reproduce with other individuals with similar characteristics to achieve the current variety of current plants and domestic animals, very different from the original shapes.


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Biology and Geology teaching materials for Compulsory Secondary Education (ESO) and Baccalaureate students.