• Question: hi Yinka, how does a certain genetic trait that a Childs parents give them deteriorate as that child has a child, then that child has a child. how long would it take fore that genetic trait to deteriorate,or if possible mutate?

    Asked by 925genm52 to Yinka on 15 Mar 2018.
    • Photo: Yinka Abejide

      Yinka Abejide answered on 15 Mar 2018:

      Hello,

      For a gene responsible for genetic trait to deteriorate or mutate, it will take about a 1000 years from the present to a million years to do so. Some factors have been shown to enhance certain mutation of genetic traits in humans. One of them is the environment; that is, exposure to radiation. This could lead to death, extinction or other deleterious effects. In some other cases, the mutation could lead to a great improvement in the population. An example of negative effect of genetic trait is the black rocket mouse; https://modeling-natural-selection.wikispaces.com/how-long-does-it-take-for-a-mutation-to-become-prevalent.
      Positive effect of a genetic trait could occur in natural selection as when a recessive gene fades out from a population and therefore can not reproduce offspring with the required allele.

Comments

  • Photo: Stéphane

    Stéphane commented on :

    The answer started good…
    Sorry Yinka … Natural selection has nothing to do with a recessive allele.
    Nature will choose who will survive depending on the trait that the individual expresses. Therefore, the trait doesn’t have to be recessive or dominant.
    For example, if 1 dominant allele leads to show the colour red on a butterfly and the colour green is the result of a double recessive. The bird will pick up more the red butterfly on the plants. Therefore, the dominant gene will not be passed into their offsprings because that butterfly is dead: this is natural selection.

  • Photo: Gemma

    Gemma commented on :

    Just wanted to make a point here as I think there are two things being slightly conflated and I want to make sure that things are clear. Genetic traits don’t deteriorate by getting diluted through the generations; that isn’t how genetics works. Versions of genes (alleles) can either stay in the population or be removed from the population depending on things like natural selection but also, and importantly, by chance (we call this genetic drift). The important thing to note here is that we don’t mix our alleles when we have kids, we pass them on as discrete units which either show up in a trait or not depending on what other alleles are present. The trait that shows up is subject to natural selection as Stephane says, but the alleles stay intact and can show up differently in a different generation when they are in a different combination. If this wasn’t the case, we’d all be getting more similar down the generations…
    When we think about population genetics, we think about the effects of mutation, and alleles disappearing from the population over time unless they are being maintained by selection, but this is quite distinct from what happens at the individual level, i.e. alleles don’t mix or get diluted when people have kids. Hope that hasn’t completely confused you…!