Genetic drift is the spread of specific random variations throughout the gene pool in the absence of specific selection pressures. There's always random variation in the population, but there aren't always changes in the environment for the population to adapt to. So natural selection, in stead of moving the population towards adaptation, might select from that random variation to move 'sideways', as it were, to a state that's equally well-adapted to the environment as what came before, but different. As random variation may produce many variants that are, more or less, equally well-adapted to their environment, the direction of evolution that results is more or less random. Because variations may spread throughout small populations faster than throughout large populations, and because a large gene pool has a stabilizing effect on the spread of variations, small populations drift faster than large populations.
small populations
Genetic drift occurs in all finite populations. However the effects of drift are more pronounced in smaller populations than in large ones. Meanwhile, even though they are more present in smaller populations, the drifting is more likely to occur in larger populations because of the larger number of different genetic combinations present. Throughout evolution of populations, genetic drifting effects all types of population sizes, though it is more likely in larger populations but more present in smaller populations.
The population needs to be small is the necessary condition for genetic drift to have a significant effect on populations.
genetic drift may occur when a small group of individuals colonizes a new habitat
Are small
Genetic drift has a larger effect on smaller populations.
Small populations.
Small populations
small populations
Genetic drift occurs in all finite populations. However the effects of drift are more pronounced in smaller populations than in large ones. Meanwhile, even though they are more present in smaller populations, the drifting is more likely to occur in larger populations because of the larger number of different genetic combinations present. Throughout evolution of populations, genetic drifting effects all types of population sizes, though it is more likely in larger populations but more present in smaller populations.
The population needs to be small is the necessary condition for genetic drift to have a significant effect on populations.
genetic drift may occur when a small group of individuals colonizes a new habitat
Are small
Genetic drift is a product of random sampling. Like all forms of sampling or selection, variation within the sample set is required. Thus for genetic drift to occur genetic change (mutation) is required. However, it would be an error to call genetic drift a product of genetic change.
genetic variation
This can occur through reproduction. If you have two people with the recessive gene for a rare genetic disorder, they have a 25% chance of having offspring with this disorder. The probability increases as the genetic pool increases.
genetic drift, mutation, natural selection, and migration