Assuming white-spotting
(S) is dominant over no-white-fur
(s):
- A heterozygous (Ss) pair has a 1/4 probability of producing 1 offspring who is no-white-fur
(ss).
- The probability of producing 2 offspring who are both no-white-fur
(ss) is 1/16.
- This is unlikely but not impossible, especially in a small population.
- Now the overall allele frequency of s in the population has increased from 50% to 100%.
If an allele frequency reaches 100%, genetic fixation occurs:
no further genetic drift is possible.
