Section 19.3 (Exam 3) Flashcards
Evolution Can Be Measured by Changes in Allele Frequencies
How is evolutionary change measured?
Looking at changes in allele and genotype frequencies
How are allele and genotype frequencies estimated?
By counting alleles and genotypes in a sample of individuals.
Allele frequency formula:
number of copies of the allele in the population/ total number of copies of all alleles in the population
If a locus has 2 alleles, A and a, what are the 3 possible genotypes?
AA, Aa, and aa.
What does it mean for a population to be polymorphic at a specific locus?
There must be two or more alleles present at that locus
If there are two alleles at a locus, and p is the frequency of one allele and q is the frequency of the other allele, what do p and q add up to?
p + q = 1
If there is one allele at a locus, what is its frequency?
1
What does it mean if a population is monomorphic at a particular locus?
There is one allele present at the locus
When a population is monomorphic at a locus, how can the allele be described?
fixed
When is an allele considered fixed?
When its frequency in a population is equal to 1.
If the conditions for the Hardy-Weinberg Equilibrium are met, how does the genetic structure of a population change over time?
it does not change
What is the Hardy-Weinberg equilibrium (HWE)?
It describes a model situation in which allele frequencies do not change
In the HWE, how can genotype frequencies be predicted?
using allele frequencies
What are the conditions that must be met for the HWE?
No mutation
No selection among genotypes
No gene flow
Population size is infinite
Mating is random
What happens if the conditions for the HWE are met?
Allele frequencies remain constant
After one generation, genotype frequencies occur in specific proportions
