more evolution: who, what, how exam key posted on class webpage check out bonuses on class webpage
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More Evolution:who, what, how
•Exam key posted on class webpage
•Check out Bonuses on class webpage
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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.
Reproductive success = evolutionary success
Individuals are selected…
But species evolve via changes in DNA during reproduction.
Who evolves?…Species.
•A population that can produce fertile offspring
•A population that does reproduce
**A population sharing genetic information**
A. harrisi A. leucurus
SeeSection
26.1
Horse
Mule
Donkey
X
=
Horse
Mule(sterile)
Donkey
X
=So…horses and donkeys are not the same species.
Who evolves?…Species.
•A population that can produce fertile offspring
•A population that does reproduce
**A population sharing genetic information**
A. harrisi A. leucurus
SeeSection
26.1
How does evolution occur?Fig 24.6
Divergent EvolutionFig 24.6
Fig 27.2
Convergent Evolution
Evolution has no goal...no ultimate life form wrong right
Fig 24.15
Natural Selection:Individuals that are most
successful at reproducing will pass on more of their genetic
information.
Natural Selection 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
Fig 24.10
Variation of a trait within a species
Three basic types of selection…
• Directional
• Stabilizing
• Disruptive
Fig 25.3
Directional Selection
Directional Selection has led to an increase in swallow size after
a cold snap
Fig 25.3
Stabilizing SelectionFig 25.4
Human birth weight has been stably selectedFig 25.4
Fig 25.5
Disruptive Selection
Disruptive Selection in blackbellied seedcrackers
Fig 25.5
Disruptive selection can lead to new species, divergent evolution
Fig 26.7
The three different types of selection
Artificial Selection
from Teosinte MaizeBy artificial selection that began ~10,000 years ago.
Fig 30.3
Wild member of 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.
Fig 1.3
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
Hunter-Gatherer
Agricultural
Industrial
Artificial Selection
(breeding)
Modern cows were bred from earlier bovine species.
Different foodsfrom one species of plant. Created byartificial 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
Next even more Evolution:the environment and randomness
•Exam key posted on class webpage
•Check out Bonuses on class webpage