Genetic Drift
Genetic drift
Genetic drift is the changes in allele frequency in a gene pool due to chance,
In each generation just be chance some individuals may leave behind more descendants (and of course genes) than other in the population meaning that more of the next generations genes will be from the luck one that reproduced more, these may not be the healthiest or the fittest individuals. This happens in all populations’ there’s no avoiding vagaries of chance. So although genetic drift is a mechanism of evolution, it does not work to produce adaptations. (101, 2014)
As an example take ten random draws from a large bag of brown and green marbles, those draws produced the following draws 5:5, 6:4, 7:3, 4:6, 8:2, 10:0, 10:0, 10:0, 10:0, 10:0, we kept drawing 10 because if the green marble failed to be represented in just one draw, it could not be got back and the we would be stuck with only the brow marbles. Below the process is depicted starting with the fourth draw.
Now imagine if the same thing was to occur in a population of animals and the gene for green were to drift out of the population, that green gene would be lost, unless a mutation or gene flow were to reintroduce the green gene.
The 10:0 situations above illustrates one of the most important effect of genetic drift: it will reduce the amount of genetic variation in a population. And subsequently with less genetic variation there is less chance of natural selection taking place, the population ends up in a situation where all its population are brown and if there is ever a time where it would be advantageous to be green they will be out of luck as the gene no longer exists in the population and so can no longer be selected for during natural selection. Natural selection can only work on what variation is already within the population; it cannot create variation. (101, 2014) additionally genetic drift plays a role in the evolution of new species.
Genetic drift is the changes in allele frequency in a gene pool due to chance,
In each generation just be chance some individuals may leave behind more descendants (and of course genes) than other in the population meaning that more of the next generations genes will be from the luck one that reproduced more, these may not be the healthiest or the fittest individuals. This happens in all populations’ there’s no avoiding vagaries of chance. So although genetic drift is a mechanism of evolution, it does not work to produce adaptations. (101, 2014)
As an example take ten random draws from a large bag of brown and green marbles, those draws produced the following draws 5:5, 6:4, 7:3, 4:6, 8:2, 10:0, 10:0, 10:0, 10:0, 10:0, we kept drawing 10 because if the green marble failed to be represented in just one draw, it could not be got back and the we would be stuck with only the brow marbles. Below the process is depicted starting with the fourth draw.
Now imagine if the same thing was to occur in a population of animals and the gene for green were to drift out of the population, that green gene would be lost, unless a mutation or gene flow were to reintroduce the green gene.
The 10:0 situations above illustrates one of the most important effect of genetic drift: it will reduce the amount of genetic variation in a population. And subsequently with less genetic variation there is less chance of natural selection taking place, the population ends up in a situation where all its population are brown and if there is ever a time where it would be advantageous to be green they will be out of luck as the gene no longer exists in the population and so can no longer be selected for during natural selection. Natural selection can only work on what variation is already within the population; it cannot create variation. (101, 2014) additionally genetic drift plays a role in the evolution of new species.