BIO 370 Lecture Notes - Lecture 15: Genotype Frequency, Allele Frequency, Genetic Drift
Random Change and Genetic Drift
In a small population, the realized genotype frequencies may differ from the expected
genotype frequencies because of random chance alone.
This is the Wright-Fisher model – for small populations, can be seen as counterpart to HW.
Gametes being paired off randomly in the smaller population, may increase or decrease the
chances of having the same allele frequencies in the gamete pool.
Genetic drift is the process of random fluctuation in allele frequencies due to sampling effects
in finite populations.
There are three general consequences of genetic drift. What are they?
1. Fluctuation in allele frequencies.
2. Decrease in heterozygosity within populations.
3. Increase in diversity among populations.
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Allele can be fixed or lost. Blue line = one of the random runs. Drift is likely to lead to fixation,
and hetereozygosity goes away. Fixed in some and lost in others.
Thee’s flutuatio, ut eause thee ae oe idiiduals there are some buffering so more
difficult for things to go to fixation.
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
In a small population, the realized genotype frequencies may differ from the expected genotype frequencies because of random chance alone. This is the wright-fisher model for small populations, can be seen as counterpart to hw. Gametes being paired off randomly in the smaller population, may increase or decrease the chances of having the same allele frequencies in the gamete pool. Genetic drift is the process of random fluctuation in allele frequencies due to sampling effects in finite populations. There are three general consequences of genetic drift. What are they: fluctuation in allele frequencies, decrease in heterozygosity within populations, increase in diversity among populations. Blue line = one of the random runs. Drift is likely to lead to fixation, and hetereozygosity goes away. The(cid:396)e"s flu(cid:272)tuatio(cid:374), (cid:271)ut (cid:271)e(cid:272)ause the(cid:396)e a(cid:396)e (cid:373)o(cid:396)e i(cid:374)di(cid:448)iduals there are some buffering so more difficult for things to go to fixation. Fluctuation also happens but dispersion takes many more generations for that to occur.