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Genetics and Evolution Genotype vs Phenotype In some environments, some phenotypes work better More fit… Bird beaks, Rock Pocket Mouse, etc

Genetics and Evolution Gene Pool? Allele Frequency? Genotype Frequency?

Genetics and Evolution Where does this variation come from? Mutations Recombination (crossing over) during meiosis Sexual Reproduction

Genetics and Evolution Tiktallik – did NOT grow legs to get away from predators!!!! Why did it ‘grow legs’?

Genetics and Evolution Single-gene Trait R/G colorblindness Duchenne MD PTC Tasting

Genetics and Evolution Polygenic Trait MOST traits If not “multiple genes”, then influenced by other genes

Genetics and Evolution Natural Selection on single-gene is pretty straight forward Single Gene does NOT mean one or two alleles; you could still have multiple alleles for a single-gene trait Some phenotypes are selected for…

Peppered Moth Single gene Single mutation – variation in a population “Originally” light with peppering on wings Single mutation increases melanin

Peppered Moth

What CAUSED the variation? What drove the selection? Try it

Peppered Moth What did ‘you’ select for? Did ‘you’ cause the variation? Change in allele frequency in a population over time

Genetics and Evolution Polygenic Traits ‘Curve’ effect Selection on polygenic traits Because it’s NOT binary…

Genetics and Evolution Directional Selection Stabilizing Selection Disruptive Selection

Genetics and Evolution What IS Genetic Drift? Why is it important? Happens by chance – ‘no’ selection Bottlenecks? Founder Effect? All three limit variation within the gene pool

Genetics and Evolution Genetic Equilibrium No net change in allele frequencies in a population = no evolution What MUST be true, for this to be true?

Genetics and Evolution Random Mating Large Population NO immigration for emigration NO Mutations NO selection How does each of these influence change in allele frequencies?

Homework Read AND NOTE section 17.3 Questions 1-2 on page 497 PLUS – How do populations become ‘reproductively isolated’? Give an example

Homework Read AND NOTE section 17.3 Questions 1-2 on page 497 PLUS – How do populations become ‘reproductively isolated’? Give an example