50 individuals = 100 alleles
25 R alleles = 25/100 = 25% R = 0.25 is the frequency of R
75 W alleles = 75/100 W = 75% W = 0.75 is the frequency of W
The sum of the frequencies for each allele in a population is always equal to 1.0!
Frequencies are percentages, and the total percentage must be 100
100% = 1.00
The percentage of each genotype present in a population
The percentage of each phenotype present in a population
Now we can define evolution as the change in genotype frequencies over time
The very stuff of evolution!
Without genetic variation, there can be no evolution
Why is phenotypic variation not as important?
Phenotypic variation is the result of:
Such as maternal or paternal effects
Not completely heritable!
Five conditions under which evolution cannot occur
All five must be met:
If any one is violated, the population will evolve!
No net change in allele frequencies due to mutation
Members of the population mate randomly
New alleles do not enter the population via immigrating individuals
The population is large
Natural selection does not occur
HWE: 5 violations
So, five ways in which populations CAN evolve!
Migration (Gene flow)
Small population sizes (Genetic drift)
Because the total of all allele frequencies is equal to 1…
If the frequency of Allele 1 is p
And the frequency of Allele 2 is q
p + q = 1