Post on 31-Dec-2015
description
Exams returned W 2/13----Bonus #1 due F 2/15
As DNA changes; traits change.
DNA Traits
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OOBacteria with mutation causing resistance
Evolution: changes in DNA as information transmitted
Changes to groups, not individuals.
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Applyantibiotic
XXX
XX X XXXX
Kills most bacteria.Except if some have mutation that allow them to be resistant.
Continues to replicate
Population of resistant bacteria
Bacteria with mutation causing resistance
Evolution: changes in DNA as information transmitted
Changes to groups, not individuals.
Evolution: A species’ genetic component changes as the individuals reproduce. These changes are based on how the DNA changes and who reproduces.
Natural Selection:Individuals that are most
successful at reproducing will pass on more of their genetic
information.
Reproductive success = evolutionary success
Are genes the only replicators?
• Ideas can act similarly to genes– Contain information
– Replicate with imperfect fidelity
Memes: transmissible ideas
Mutations
• Ideas can act similarly to genes or viruses– Contain information
– Replicate with imperfect fidelity
Memes: transmissible ideas
• Ideas can act similarly to genes or viruses– Contain information
– Replicate with imperfect fidelity
Memes: transmissible ideas
Evolve: most successful replicators become most abundant
Contrasts between memes and genes
Genes• Slow replication
• High copy fidelity
• Universal in organisms
Memes• Rapid replication
• Low copy fidelity
• Limited to some organisms– Only humans can
transmit complex memes?
Selection of memes and genes can be at odds
NvN chpt 8
Evolution of memes and genes
Humans can pass on genes and/or memes
Do memes make humans unique?
Human Population Growth
Natural Selection:Individuals that are most
successful at reproducing will pass on more of their genetic
information.
Artificial Selection:Individuals chosen by humans will reproduce and pass on their
genetic information.
from Teosinte MaizeBy artificial selection that began ~10,000 years ago.
Wild Brassica oleracea: small side buds
Brussels sprouts: extremely large side buds
Artificial selection
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f In
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idu
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Size of buds (cm)
0 1 2 3
1. Select individuals that have the largestside buds and breed them.
2. Of the offspring, select individuals that have the largest sidebuds and breed them.
3. Of the offspring,select individuals that have the largest sidebuds and breed them.
4. After severalgenerations, bud sizeincreases dramatically.
Wild Brassica oleracea: small side buds
Brussels sprouts: extremely large side buds
Artificial selection
Nu
mb
er o
f In
div
idu
als
Size of buds (cm)
0 1 2 3
1. Select individuals that have the largestside buds and breed them.
2. Of the offspring, select individuals that have the largest sidebuds and breed them.
3. Of the offspring,select individuals that have the largest sidebuds and breed them.
4. After severalgenerations, bud sizeincreases dramatically.
Selection only works if there is variability in the
population
Different foodsfrom one species of plant. Created byartificial selection.
CB 22.10
Individuals are selected…
But populations evolve via changes in DNA during reproduction.
Evolution can only occur when both of these conditions are met:
•Genetic diversity gives rise to individuals with different traits
and•Not all individuals can reproduce
CB 22.9
CB 23.11
Variation of a trait within a species
Three basic types of selection…
• Directional
• Stabilizing
• Disruptive
CB 23.12
Directional Selection
Directional Selection has led to an increase
in swallow size
CB 23.12
Stabilizing Selection
Human birth weight has been stably selected
CB 23.12
Disruptive Selection
Disruptive Selection in blackbellied seedcrackers
CB 23.12 The three different types of selection
Evolution:A species’ genetic component changes as the individuals reproduce due to…
•Non-random changes (natural selection)•Random changes (genetic drift/bottleneck)
•Mutations add new alleles or genes
Exams returned W 2/13----Bonus #1 due F 2/15