Download The Hardy-Weinberg Principles

The Hardy-Weinberg
Principles
Changing Populations
Evolution
• Evolution is caused by the changing of
populations.
Changing Populations
• Populations change at the genetic level. To get
the population to change the gene pool must
change.
Gene Pool
• Gene pool- all of the alleles in a population
Ex. 500 Flowers(show incomplete dominance)
320 RR (red)
160 Rr (pink)
20 rr (white)
Allele Frequency
• Allele frequency is the proportion of each allele
found in the gene pool.
• p = one allele (usually dominant)
• q = the other allele (usually recessive)
Ex. What would the allele frequency be for “R”
and “r” in the wild flower population?
Hardy-Weinberg Equation
• This equation shows the frequency of each
genotype we would expect to see based on the
allele frequencies in the population.
• p2 + 2pq + q2= 1
Ex. What would the genotype proportions be in
the flower population?
Hardy-Weinberg Equilibrium
• If the genotype frequencies in the actual
population match the proportions in the
equation, then the population is in Equilibrium
and not evolving.
• Ex. Is the flower population Evolving?
5 conditions
• For a population to stay in equilibrium (not
evolve) five things must be true.
• 1 No Mutations
• 2 Random Mating (no sexual selection)
• 3 No Natural Selection
• 4 No Gene flow
• 5 Very Large Population (no Genetic Drift)
• These five things change the proportion of
genotypes or the allele frequencies
Example
• In a population of 300 Snakes 130 are
homozygous dominant for black scales. 70 are
homozygous recessive and have red scales.
100 are Heterozygous are have a checker
board pattern. Is this population evolving?