1. Aim: How does classical genetics affect the theory of evolution?

2. Did Darwin know anything of Mendel’s work of Classical Genetics? NO!!!! Darwin understood the connection between natural selection and adaptation to the environment. However, he could not explain how the variations that are the basis for natural selection pass from one generation to the next. Darwin Mendel

3. What was the result? Natural Selection + Genetics Population Genetics Remember, individuals do not evolve, populations do. Population- a group of individuals of a single species that live in a specific area.

4. What is Population Genetics? The study of changes in the genetic makeup of populations. An important concept in population genetics is the Gene Pool: All the alleles (alternative forms of genes) in all the individuals that make up a population.

5. What is the significance of a population’s gene pool in evolution? The gene pool is the “reservoir” from which the next generation draws its genes. The population’s gene pool is also where genetic variation (the raw material of evolution) is stored. The variation in phenotype (appearance) of this population of flowers is determined by the combination of alleles in the gene pool. The phenotype of the offspring are also determined by the alleles in the gene pool.

6. What is Allele Frequency? How often certain alleles occur in the gene pool (usually expressed as a percentage). R = 14/20 (70%) r = 6/20 (30%)

7. The Hardy-Weinberg Law: The condition in which allele frequencies do not change from one generation to the next. The population is said to be in genetic equilibrium. Ex: A population of two individuals has the following genotype: Rr and Rr. 1)What is the allele frequency of R? 2)What is the allele frequency of r? 3)What are the predicted genotypes of their offspring? 4)What are the allele frequencies of the population of the offspring? **Sexual Reproduction alone does not affect Genetic Equilibrium

8. Hardy-Weinberg Equation: p2 + 2pq + q2 = 1 and p + q = 1 p = frequency of the dominant allele in the population q = frequency of the recessive allele in the population p 2 = percentage of homozygous dominant individuals q 2 = percentage of homozygous recessive individuals 2pq = percentage of heterozygous individuals

9. What happens when changes do occur to the gene pool (frequencies of alleles change) from one generation to the next? EVOLUTION

10. What leads to changes in the gene pool? 1)Genetic Drift- a change in a gene pool due to chance. **Causes changes in gene pools in small populations. 2)Mutation- changes in DNA lead to changes in allele frequency. 3) Gene Flow (Migration)- as individuals move into a population, they bring in genes not already present. As individuals move out of a population, they take genes out of a population.

11. What leads to changes in the gene pool? 4)Natural Selection- the reproductive success of some organisms within a population can also change allele frequencies (gene pool).

12. What conditions must be met for the Hardy-Weinberg Law to hold true? The gene pool remains the same from generation to generation. 1) The population must be large. In a small population, alleles of low frequency may be lost due to genetic drift. 2)Individuals must not migrate into or out of a population. 3)Mutations must not occur. 4)Reproduction must be completely random. This means that every individual, whatever its genetic, makeup, should have an equal chance of producing offspring (no natural selection).

13. Why is the Hardy-Weinberg Law useful when it can’t apply to real world situations? It is important because it allows us to discover whether or not evolution is occurring in a population. Change in allele frequencies (gene pool) = Evolution Microevolution- is evolution on the smallest scale – a generation-to-generation change in the frequencies of alleles within a population. Macroevolution- major biological changes that are clearly visible.