PHENOTYPE VS. GENOTYPE

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PHENOTYPE VS. GENOTYPE
Phenotype Genotype Environment
Trait DNA Development
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PHENOTYPE VS. GENOTYPE
Nutrition Exercise
Height

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PHENOTYPE VS. GENOTYPE
Eye color

0
Phenotype genotype
Trait is 100 heritable
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PHENOTYPE VS. GENOTYPE
Sperm donation behavior
Enviro

0

Phenotype environmentally determined
Trait is 0 heritable
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HERITABILITY
A phenotypic trait is heritable if there is a
genotypic component
Heritability ranges from 0-100
Heritability must be gt 0 for natural selection to
occur
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RATE OF EVOLUTION
Rate of change in trait is determined by
1. Heritability
2. Strength of selection
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3. GENETIC VARIATION
2 sources of variation mutation and recombination
Mutation is ultimate source
Vast majority of mutations are bad
Occasionally they are good
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3. GENETIC VARIATION
Recombination
Sexual reproduction
New genetic combinations
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GENETIC DIVERSITY
How is genetic diversity maintained?
Polymorphism more than 1 form of a trait exists
in a population
1. Different forms may be advantageous in
different situations
2. Different forms may be selectively neutral
3. Heterozygote may have fitness advantage
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HETEROZYGOTE ADVANTAGE
Sickle-cell anemia
Recessive mutation in a-globin
A dominant normal allele
a recessive variant (sickle)
80 of aa individuals die before reproducing
Haldane noticed map of sickle-cell frequency
matched with malaria
Aa individuals are resistant to malaria!
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4. DIFFERENTIAL FITNESS
Fitness the proportion of genes that an
individual leaves in the gene pool of a
population
Individuals with the greatest fitness leave the
largest numbers of offspring
kids
Frequency of your alleles
Your fitness
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4. DIFFERENTIAL FITNESS
Each pair had 2 offspring trait is selectively
neutral
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4. DIFFERENTIAL FITNESS
Different alleles have different fitness
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REVIEW QUESTION
children (fitness)
Education level
? Women with more education have fewer children
? Fitness of educated women is less than
uneducated women
? Should society become dumber over time???
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MISCONCEPTIONS
1. Organisms strive for higher fitness goal
oriented
- Evolution is a mindless, mathematical process
with no ultimate goal
- All living things are subject to selection
what we see today is not the end point
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MISCONCEPTIONS
2. Adaptations occur for the good of the
species
- Selection acts at the level of the INDIVIDUAL,
not the population!
- Individual traits are selected for or against
sum total determines individual fitness
- Evolution is the change in frequency of traits
over time for individuals in a population