Chap 23 Evolution of Populations

Genotype p2p2 AA 2pqAa q2q2 aa Phenotype Dominantp 2 + 2pq Recessiveq2q2 Gene pA qa p + q = 1 p 2 + 2pq + q 2 = 1

5 Conditions of the Hardy- Weinberg Principal If all conditions are met then the gene frequencies stay the same (equilibrium) 1.Populations must be large 2.Random mating 3.No natural selection 4.No mutation 5.No migration

1.Why are there no plants with white flowers in Generation 3? No individuals that carried the allele for white flowers in Generation 2 produced offspring.

2.If one RR plant and one rr plant where the only individuals that reproduced in Generation 2, would genetic drift have occurred between Generations 2 and 3? Explain. No. The allele frequencies would still be 50% R and 50% r. Genetic Drift: when gene frequencies change due to random events

HW Problems problems animation

Bottle Neck Effect

Sample of Original Population Founding Population A Founding Population B Descendants Genetic Drift a random change in gene frequency Section 16-2

Sample of Original Population Founding Population A Founding Population B Descendants Section 16-2 Founder’s Effect

Sample of Original Population Founding Population A Founding Population B Descendants Founder’s Effect Section 16-2

Cline-Change in phenotype over a geographic range

Normal Distribution Bell curve Normal Distribution Bell curve

Different combinations of survivors will be bring different combinations of genes together resulting in the appearance of new phenotypes

p456 Balanced Polymorphism Heterozygote Advantage - People with sickle cell trait have a better chance of surviving Malaria Freq dependent Selection One morph declines if it becomes too common p456 Balanced Polymorphism Heterozygote Advantage - People with sickle cell trait have a better chance of surviving Malaria Freq dependent Selection One morph declines if it becomes too common

Secondary Sex characteristics may not be seem adaptive - but it does make the individuals more FIT. Darwinian fitness Secondary Sex characteristics may not be seem adaptive - but it does make the individuals more FIT. Darwinian fitness

Sexual Dimorphism

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