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23.4 Genetic Drift
Explain the effects of genetic drift over time.
The founder effects are compared and contrasted.
Genetic drift can lead to widespread genetic changes in a population.
Let's look at the second important way the gene pool of a popu is in a population.
The number of lation can change.
The blue line shows a population in which N is 1,000, while the red line shows a population in which N is 10.
10 is fixed.
Chapter 23 fluctuated from generation to generation.
The populations consisted of only black and white mice.
The population begins to drift.
When the sample size is large, the relative effect of random chance is much smaller.
Even in large populations, genetic drift can lead to allele loss or fixation, but it will take many more generations to occur than it does in small populations.
When the size of a population decreases, genetic drift may change frequencies.
The founder effect is one of two examples of this phenomenon.
The destruction of habitat is caused by a dry spell.
The population size is decreased and the dark position may be eliminated by these occurrences.
The population has passed through a bottle green state.
Some alleles may be over-represented.
Changes may happen for two reasons.
The original population that was much larger had allele frequencies that were different from those of the surviving population.
The popula tion may regain its original size after going through a bottleneck.
The new population is likely to have less variation in their genes.
The popu phenotypes are left in this example.
The dark green vari ety is lost due to a shortage.
Due to hunting, the population decreased to 20 to 30 members in the 1890s.
The species rebounded in numbers to over 100,000, but its genetic variation was reduced to very low levels.
In this example, a population of Frogs establishes a colony in a new location.
A few individuals from a large population on a continent may move because of the reduced population size.
The founding of an island population can be achieved by reducing the genetic diversity in the island.
The reduction in pop efforts of biologists who are trying to save species nearing ulation size is related to the new location.
There are two consequences of the founder effect.
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