Mechanisms of Evolution Hardy-Weinberg Law

 The Hardy–Weinberg principle states that the genotype frequencies in a population remain constant or are in equilibrium from generation to generation unless specific disturbing influences are introduced.genotype

Hardy-Weinberg Law  Hardy–Weinberg equilibrium is an ideal state that provides a baseline against which change can be analyzed

Hardy-Weinberg Law  Genotype -This is the "internally coded, inheritable information" carried by all living organisms. Genotype  "blueprint" or set of instructions for building and maintaining a living creature.

Hardy-Weinberg Law  Population – all members of a species living in one locale The occurrence of evolution within a population is established by determining that the genetic makeup of the population has changed.

Hardy-Weinberg Law Most common conditions that cause a change in gene pool frequencies Mutation Gene flow Nonrandom mating Size of population Natural selection

Hardy-Weinberg Law  Mutations Changes in the way cells function or develop, caused by an inherited genetic defect or environmental exposure.

Hardy-Weinberg Law  Gene flow the natural transfer of genes from one population into the genetic makeup of another population through hybridization and interbreeding  migration or the dispersal of seeds and pollen

Hardy-Weinberg Law Non-random mating -Mating that has not occurred due to chance, and therefore has had human interference

Hardy-Weinberg Law Population Size Population must of a sufficient size so that the laws of probability apply

Hardy-Weinberg Law  Natural selection – occurs when a new variation arises that allows certain members of a population to capture more resources.

Hardy-Weinberg Law  Equation for calculating gene pool frequencies p 2 + 2pq + q 2 = 1

Hardy-Weinberg Law p 2 = frequency of AA  ( homozygous dominant)  Two dominant alleles 2pq = frequency of Aa  (heterozygous)  Two different alleles one dominant, one recessive q 2 = frequency of aa  ( homozygous recessive) two recessive alleles

Hardy-Weinberg Law  Remember: Dominant phenotype characteristics are displayed by both:  Homozygous dominant & heterozygous genotypes ( homozygous dominant) Two dominant alleles (heterozygous) Two different alleles one dominant, one recessive

Hardy-Weinberg Law  Example : Determine the Population that is heterozygous for white coat  *ALLELE FOR BLACK COAT IS RECESSIVE

Hardy-Weinberg Law  12 white  4 black 1. CALCULATE q 2 *Count the individuals that are homozygous recessive *calculate the percentage of the total population they represent. THIS IS q 2 4 of the 16 cats show the recessive phenotype which is 25% or 0.25 q 2 =. 25

Hardy-Weinberg Law  12 white  4 black 2. Find q Take the square root of q 2 to obtain q, the frequency of the recessive allele q =.5

Hardy-Weinberg Law  12 white  4 black 3. Find p The sum of the frequencies of both alleles =100% We know q =.5 So if p+q=1 ( a population in genetic equilibrium) Then p =.5

Hardy-Weinberg Law  12 white  4 black 4. Find 2pq The frequency of the heterozygotes is 2pq which is the percent of the population that is heterozygous for white coat: 2pq= 2(.5) (.5) =.50 50% is heterozygous for white coat

Hardy-Weinberg Law  In class today/homework:  Finding a frequency of certain allele. Specific allele/ total population of alleles

Hardy-Weinberg Law  WHY is this important????????  Based on these equations, we can determine useful but difficult-to-measure facts about a population. matters/animals/blogs/100- years-later-the-passenger- pigeon-still-haunts- us#ixzz3Bc4dEeCH

Hardy-Weinberg Law  WHY is this important???????? Cancer Autism Downs syndrome