population: 10 individuals phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)
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![Page 1: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/1.jpg)
Population:10 individuals
Phenotype frequency:30% blue eyes (or 0.3)70% brown eyes (or 0.7)
![Page 2: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/2.jpg)
Population10 individuals
Phenotype frequency:30% blue eyes (or 0.3)70% brown eyes (or 0.7)
= bb
= BB
= Bb
Genotype frequency:f(bb) = 30% (or 0.3)f(Bb) = 50% (or 0.5)F(BB) = 20% (or 0.2)
![Page 3: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/3.jpg)
Population10 individuals
= bb
= BB
= Bb
Genotype frequency:f(bb) = 30% (or 0.3)f(Bb) = 50% (or 0.5)f(BB) = 20% (or 0.2)
b b b bb b
B b
B b
B b
B b
B b
B B B B
Number of alleles:b = 11B = 9
![Page 4: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/4.jpg)
Population10 individuals
Genotype frequency:f(bb) = 30% (or 0.3)f(Bb) = 50% (or 0.5)f(BB) = 20% (or 0.2)
b b b bb b
B b
B b
B b
B b
B b
B B B BNumber of alleles:b = 11B = 9
bb
bb
b
b
Bb
Bb
Bb
Bb
Bb
BB
BB
Allele frequency:f(b) = 11/20 = 0.55f(B) = 9/20 = 0.45
![Page 5: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/5.jpg)
bb
bb
b
b
Bb
Bb
Bb
Bb
Bb
BB
BB
=
Gene pool of a population
![Page 6: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/6.jpg)
= bb
= BB
= Bb
b b b bb b
B b
B b
B b
B b
B b
B B B B
Possible gametes of each individual
![Page 7: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/7.jpg)
bb
bb
b
b
Bb
Bb
Bb
Bb
Bb
BB
BB
=
Possible gametes in the population
![Page 8: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/8.jpg)
Population10 individuals
Genotype frequency:f(bb) = 30% (or 0.3)f(Bb) = 50% (or 0.5)f(BB) = 20% (or 0.2)
b b b bb b
B b
B b
B b
B b
B b
B B B BNumber of alleles:b = 11B = 9
bb
bb
b
b
Bb
Bb
Bb
Bb
Bb
BB
BB
Allele frequency:f(b) = 11/20 = 0.55f(B) = 9/20 = 0.45
![Page 9: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/9.jpg)
Genetic Drift
(a) Founder effect
(b) Genetic bottleneck
High mortalitystrikes
individualsat random
Time 1 Time 2
Bottleneckedpopulation is likelyto have differentallele frequenciesthan originalpopulation,by chance
New populationis likely to havedifferent allelefrequenciesthan the sourcepopulation,by chance
Immigrantsestablish new
population
Homozygous for allele A1
Homozygous for allele A2
Heterozygous
![Page 10: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/10.jpg)
Time 1
Population 1
At time 1,populationsdiffer in allelefrequencies
Gene flowcauses allelefrequenciesin the twopopulationsto be more alike
Time 2
Population 2
Population 1 Population 2
Homozygous for allele A1Homozygous for allele A2
Geneflow
Geneflow
Gene Flow
![Page 11: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/11.jpg)
(a) Directional selection changes the average valueof a trait.
Before selection
During selection
Normal distribution
Nu
mb
er
of
ind
ivid
ua
ls
Lowfitness
Highfitness
Change inaveragevalueAfter selection
Value of a trait
![Page 12: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/12.jpg)
Figure 25-3 Slide 6
Original population(N = 2880)
Body size class
For example, directional selection caused averagebody size to increase in a cliff swallow population.
Per
cen
tag
e o
f b
ird
s
Change inaveragevalue
Survivors(N = 1027)
![Page 13: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/13.jpg)
![Page 14: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/14.jpg)
(a) Stabilizing selection reduces the amount ofvariation in a trait.
Normal distribution
Before selection
During selection
After selection
Nu
mb
er
of
ind
ivid
ua
ls
Value of a trait
Lowfitness
Lowfitness
Reductionin variation
High fitness
![Page 15: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/15.jpg)
(b) For example, very small and very large babies are themost likely to die, leaving a narrower distribution of birthweights.
Pe
rce
nta
ge
of
ne
wb
orn
po
pu
lati
on
Mortality
Birth weight (pounds)
Pe
rce
nta
ge
of
mo
rta
lity
Heavymortalityon extremes
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(a) Disruptive selection increases the amount of variationin a trait.
Normal distribution
Before selection
During selection
After selection
Nu
mb
er
of
ind
ivid
ua
ls
Value of a trait
HighHighfitnessfitness
Highfitness
Increase invariation
Low fitness
![Page 17: Population: 10 individuals Phenotype frequency: 30% blue eyes (or 0.3) 70% brown eyes (or 0.7)](https://reader035.vdocuments.site/reader035/viewer/2022062720/56649f175503460f94c2e3a2/html5/thumbnails/17.jpg)
(b) For example, only juvenile black-bellied seedcrackers thathad very long or very short beaks survived long enough tobreed.
Only theextremessurvived
Only theextremessurvived
Nu
mb
er
of
ind
ivid
ua
ls
Beak length (mm)