Ed asked in Science & MathematicsBiology · 4 weeks ago

Explain why it is that although populations evolve, and individuals do not, it is the individual that natural selection acts upon? ?

Why does it work at the level of the individual?

3 Answers

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  • Cowboy
    Lv 6
    4 weeks ago

    Evolution is a genetic change in a population over generations - individuals do not experience genetic change and only live a single lifetime and so cannot evolve.

  • Anonymous
    4 weeks ago

    Individuals do evolve. All mutations happened within a single individual. It is then spread through the rest of the population if the mutation is advantageous but it is eliminated if the mutation is deleterious. The population is simply the sum total of all individuals within it. If most individuals have the same phenotype at one point in time, and they have a different phenotype in the future, then it is called evolutionary change.

    Each individual will have a different chance of survival based on the traits that it has. Each individual therefore is selected for or against. It is the sum total of the outcomes of these selection events that shapes the gene frequencies within a population. Take the pepper moth for example, some individuals may be light colored, and some dark. Natural selection will act on each individual and the outcome depends on the color morph the moth has. The population may shift from mostly dark moths to mostly white morphs not in a single instant, but it takes a lot of different events for there to be a change. If for example a hundred birds hunted for moths and they ate mostly light colored or dark colored moths, then the population may then change, and there may then be more dark colored or light colored moths in the next generations. After many generations, the population may have changed, or it may not.

    • Ted K
      Lv 7
      4 weeks agoReport

      No--individuals do not evolve. The alleles they have when they're born are always the same ones they have when they die. So, by definition they can't evolve, because evolution is DEFINED as change in allele frequencies in a POPULATION of organisms over time.

  • Ted K
    Lv 7
    4 weeks ago

    Because it's the individual which is either going to reproduce or not.  It's that individual's inherent genetic content that is either going to get passed on into the population or pass out of it and be lost.  You multiply that by all the individuals within that population, and the end result is a change in predominating gene frequencies in that group--which is the very definition of evolution.

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