The%20Sexual%20Life%20Cycle%20in%20Animals

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The 23 Pairs of Homologous Chromosomes of Humans
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Chromosome Number in Selected Eukaryotes
Number of Chromosomes
Number of Chromosomes
Division
Division
Vertebrates Opossum 22 Toad 22 Salamander 24 Frog
26 Vambire bat 28 Lungfish 38 Mouse 40 Rat 42 Huma
n 46 Chimpanzee 48 Orangutan 48 Gorilla 48 Cow 60
Horse 64 Black bear 76 Chicken 78 Dog 78 Duck 80
Fungi Penicillium 4 Neurospora 7 Dicyostelium 7 Sa
ccharomyces (a yeast) 18 Insects Mosquito 6 Droso
phila 8 Housefly 12 Honeybee 32 Silkworm 56 Plants
Haplopappus gracilis 2 Barley 14 Garden
Pea 14 Corn 20 Bread wheat 42 Tobacco 48 Sugarcane
80 Horsetail 216 Adders tongue fern 1262
Table 10-1
A wide range of organisms is presented to
demonstrate the very different values that are
possible. The number of chromosomes in the body
cells of most eukaryotes falls between 10 and 50.
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Genome Size and DNA Content of Some Organisms
Percent of DNA That Codes for Something
Genome Size (Base Pairs x 109)
Organism
Total Coding DNA
Bacterium (Escherichia coli) Yeast
(Saccharomyces) Roundworm (Caenorhabditis) Fruit
fly (Drosphila) Newt (Triturus) Human
(Homo) Lungfish (Protopterus) Mustard
(Arabidopsis) Lily (Fritillaria)
000.0004 000.0009 000.09 000.18 019.0 003.5 140.0
000.2 130.0
100 70 25 33 1.5-4.5 9-27 0.4-1.2 31 0.02
0.00004 0.00063 0.023 0.059 0.29-0.855 0.32-0.945
0.56-1.18 0.062 0.026
Table 23.3
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Spermatogenesis and Oogenesis in Mammals
Spermatogenesis produces four viable sperm,
wheres oogenesis produces one egg and at least
two polar bodies. In humans, both sperm and egg
have twenty-three chromosomes each therefore,
following fertilization, the zygote has forty-six
chromosomes.
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Paternal
Maternal
Alignment at metaphase
3 paternal 6 maternal
6 paternal 3 maternal
In the reductional division of meiosis the
alignment of paternal and maternal chromosomes is
random. Since the alignment of the chromosomes
is in two planes, each planes will contain some
paternal and some maternal.
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Meiotic Nondisjunction During Reduction Division
2N 4
2N 4
N 2
N 2
N - 1 1
N 1 3
Normal Disjunction in Reductional Division
Reductional Division Nondisjunction
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All The Children in These Photographs Have Downs
Syndrome
As is evident in a and c, the facial features
characteristic of Downs syndrome.
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Correlation Between Maternal Age and the
Incidence of Down Syndrome
As women age, the chances they will bear a child
with Down syndrome increase. After a woman
reaches age 35, the frequency of Down syndrome
increases rapidly.
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Selective Forces Operating in Humans
Conception
Liveborn
Pregnancy Loss
Natural selection operates in human populations
to ensure the reduced survival and minimal
reproductive potential of individuals with major
chromosomal abnormalities
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Effects of Nondisjunction of the Sex Chromosomes
During Meiosis
Nondisjunction in Father
Sex Cromosomes of Defective Sperm O XX YY XY
Sex Chromosomes of Normal Egg X X X X
Sex Chromosomes of Offspring XO XXX XYY XXY
Phenotype Female Female Male Male
Nondisjunction in Mother
Sex Chromosomes of Normal Sperm X Y X Y
Sex Chromosomes of Defective Egg O O XX XX
Sex Chromosomes of Offspring XO YO XXX XXY
Phenotype Female Dies as embryo Female Male
Trisomy X (XXX)
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Maternal age effect in syndromes due to
nondisjunction of X chromosomes XXY and XXX
combined 153 cases from the United Kingdom
(Court Brown 1967 21)
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In Spontaneous Abortions
400
Karyotype normal
Karyotype abnormal
300
Number of Specimens Studied
200
100
0
2
3
4
5
6
7
8
9
10-12
Weeks of Development
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Freckles
No Freckles
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A Cross Showing Incomplete Dominance in Red,
White, and Pink Snapdragons
The pink color results from incomplete dominance
of the red allele over the white allele.
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Long Purple (Double Dominant)
Short White (Double Recessive)
x
TT PP
tt pp
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F2 Phenotypes
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Independent Assortment in the Budgie
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Human Skin Color is a Result of Polygenic In
heritance
Northern Europeans Whites
African Blacks
P
Children of Mixed Marriages
F1
Mating of F1 Individuals
F2
Amount of Dark Pigment in the Skin
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An Example of Environmental Effects on Phenotype
Two plants of the same species (Hydrangea
macrophylla) may carry the same alleles for
flower color. Even so, the color of their floral
clusters may vary from pink to blue depending
on the acidity of the soil in which a plant
happens to be growing.
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Relationship
Relationship
I.Q. Similarity
Identical Twins
Raised Together
Identical Twins
Raised Apart
Fraternal Twins
Raised Together
Siblings
Raised Together
Siblings
Raised Apart
Together
Parent-Child
Unrelated (Parent-Adoptee)
Together
Unrelated
Raised Together
Raised Apart
Unrelated
0.0
0.2
0.6
0.8
1.0
0.4
The more closely two people are related, either
genetically or socially, the more similar their
IQ level is. In this graph, similarity in
genetic background and familial upbringing is
compared with similarity in IQ, on a scale of 0
(no relationship between IQ scores) to 1 (exactly
the same score). The bars represent the range of
results from different studies, while the crosses
mark the average similarity for all the studies,
while the crosses mark the average similarity for
all the studies.
(Modified from Bouchard and McGue, Science 1981
2121055-1058.)
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Correlations for Height and Weight Between Twins
Raised Together and Apart  
The Correlations Given Here Are Averages Over the
Three Largest Studies
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Estimates of H From Monozygous and Dizygous Twin
Data
Data from Osborne and DeGeorge (1959)
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Incidence of Alcoholism () in Half-siblings of
Alcoholic Probands According to Their Biological
and Rearing Parents
Half-sib Alcoholic ()
Biological Parent Alcoholic Alcoholic 46 Non-Alcoh
olic 50 Biological Parent Non-Alcoholic Alcoholic
14 Non-Alcoholic 8
Rearing Parent
Rearing Parent
(from M.A. Shuckit, D.W. Goodwin and A. Winokur
(1972) American Journal of Psychiatry 128, 122)
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Parent-Child and Sib-Sib Correlations in IQ in
Three Recent Adoption Studies
Adoptive Children
Biological Children
Study
Minnesota I
Minnsota II
Texas
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Concordance Rates of MZ and DZ Twins for
Criminality In Studies from Various Populations
100
80
60
Concordance
40
20
Number of MZ DZ
4
5
13
17
4
5
37
28
31
43
18
19
28
18
67
14
14
28
1932
1929
1939
1934
1936
1936
1961
1968
Research
Holland
Germany
Finland
USA
Germany
Japan
Denmark
From Fuller and Thompson 1978 63, and some
additions
as Defined by Court Conviction
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Frequencies of MN Blood Types in Various Human
Populations
Number Observered
Allele Frequencies
MN 32 216 481 74 52
N 269 492 186 17 4
p(LM) 0.059 0.178 0.553 0.734 0.917
q(LN) 0.941 0.822 0.447 0.266 0.083
Sample 303 730 954 203 361
M 2 22 287 112 305
Population New Guinea highlands Australian
Aborigines New York City whites Guatemalan
Indians Navaho Indians (U.S.)
Table 7.4
Gene Frequencies in Populations
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Observed and Expected Numbers and Frequencies of
MN Blood Types in a Sample Population of 613
White Americans
Table 7.3
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Non-inherited Variation

• 1. Individual variation in time
• (a) Age variation
• (b) Seasonal variation of an individual
• (c) Seasonal variation of generations
• Social variation (insect castes)
• 3. Ecological variation
• (a) Habitat variation (ecophenotypic)
• (b) Variation induced by temporary
  environmental conditions
• (c) Host-determined variation a
• (d) Density-dependent variation a
• (e) Allometric variation a
• (f) Neurogenic color variation
• Traumatic variation
• (a) Parasite induced a
• (b) Accidental and teratological variation a

a For details, see Mayr, Linsley, and Usinger
(1953)
Table 7.1
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Mutation Rates for a Sampling of Gene Loci
Table 21.2
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Parental Age and Mutation Rate
b
a
gt45
40-44
35-39
Age of Fathers (Years)
30-34
25-29
lt25
1
2
3
4
5
0
Relative Incidence of Mutations
This graph shows the relative incidence of some
dominant mutations among individuals, grouped
according to the fathers age at the birth of the
mutant offspring the vertical bars represent
intervals of error. Curve a shows the incidence
of achondroplasia curve b shows the incidence of
neurofibromatosis and some other dominate genetic
diseases. Curve a shows a striking effect of the
fathers age on the rate of occurrence of the
dominant mutation for achondroplasia curve b is
given for comparison. (From F. Vogel, Genetics
Today, vol. 3, p. 838, Oxford Pergamon, 1965.)
Figure 8.4
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Estimated Relative Mutation Rate in Europe
Relative Mutation Rate (1level when all fathers
are lt 30)
Fathers gt 35 Years ()
1.22 1.22 1.27 1.28 1.33 1.34 1.35 1.38 1.43 1.44
1.45 1.47 1.47 1.47 1.53 1.53 1.53 1.53 1.54 1.57
1.64 1.64 1.69 1.69 2.67
7.3 8.5 9.6 10.2 11.t 12.0 12.1 12.9 14.9 15.4 16.
0 17.6 17.8 17.6 21.1 19.0 20 23.4 19.8 22.2 23.6
24.1 24.3 33.5 46.1
Table 11.10
From Modell Kuliev (1990)
a Correlation for infants born out of wedlock
does not alter the figure
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Genes
Relative Vigor of the Standard Strain 50 and six
mutant types of Antirrhinum Majus Under Different
Environmental Conditions
Environments (conditions specified below)
Table 8
Bruecher (1943) Gustafsson (1951)
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Random Events In Population Genetics
Small population (2N 18)
1
0.8
0.6
Gene Frequency
0.4
0.2
0
0
4
8
12
16
20
Generation
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Random Genetic Drift
110
30
20
Number of Populations
10
0
0
4
8
12
16
20
24
28
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Number of bw75 alleles
Random genetic drift in 107 actual populations of
Drosophila melanogaster. Each of the initial 107
populations consisted of 16 bw75/bw heterozygotes
(N 16 bw brown eyes). From among the
progeny in each generation, 8 males and 8 females
were chosen at random to be the parents of the
next generation. The abscissa of each histogram
gives the number of bw75 alleles in the
population, and the ordinate gives the
corresponding number of populations. (Data from
Buri, 1956.)
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Figure 20.3 Genetic drift experiment. At the
beginning of this experiment, each of 107
Drosophila populations had eight heterozygous
flies (bw75/bw, bw brown eyes) of each sex.
From the many offspring in each generation, only
eight females and eight males were chosen at
random to be the parents of the next generation.
Nineteen generations later, 50 of the
populations had fixed alleles.
In the first generation, most populations
have many heterozygotes.
1
2
3
4
5
6
7
8
9
30
Generation
10
11
12
20
13
In the nineteenth generation, 25 of the
populations have only recessive homozygotes and
25 have only dominant homozygotes.
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Number of populations
15
16
10
17
18
19
0
0
5
10
15
20
25
30
32
Number of bw75 Alleles
homozygous recessive phenotype
homozygous dominant phenotype
heterozygous phenotype
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Table 34.1 Genetic Drift and the Dunkers
Type Blood Population Population Population
Type Blood U.S. Dunker European
ABO system
A 40 60 45
BAB 15 5 15
Rh- 15 11 15
MN system
M 30 44.5 30
MN 50 42 50
N 20 13.5 20
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Genetic Drift Frequency of the ABO blood-group
alleles in Eskimo populations in Greenland
(Laughlin 1950)
Allele Frequency () Allele Frequency () Allele Frequency ()
Region IA IB IO
Nanortalik, Julianehaab District, southern Greenland 27 3 70
South of Nanortalik 35 5 60
Cape Farewell 33 3 64
Jakobshavn 29 5 66
Angmagssalik, eastern Greenland 40 11 49
Thule, northern Greenland 9 3 84
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Original population
Bottleneck Effect
Bottleneck Effect A Dramatic Reduction in
Population Size Leads to Reduced Genetic
Variability. Ancestral cheetahs probably had
normal levels of genetic variability, represented
in the bottle by the three alleles A, a, and ?
and the six genotypes AA, Aa, aa, A?, a? and ?? .
Population bottleneck
Chance survivors
New population of descendants
Figure 33.16
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The Bottleneck Effect
1. The original population has approximately
equal frequencies of red and yellow alleles.
2. A chance environmental event greatly reduces
the population size.
3. The surviving individuals have different
allele frequencies from the original population...
4. ...which generates a new population with more
red than yellow alleles.
Population bottlenecks occur when only a few
individuals survive a random event, resulting in
a shift of allele frequencies within the
population.
21.8
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Characteristics of Several Mating Systems
Mating system Defining feature
Random mating Choice of mates independent of genotype and phenotype
Positive assortative mating Mates phenotypically more similar than would be expected by chance
Negative assortative mating (disassortative) Mates phenotypically more dissimilar than would be expected by chance
Inbreeding Mating between relatives
Table 4
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Inbreeding Depression in Rats
Year Nonproductive matings (per cent) Average litter size Mortality from birth to 4 weeks (per cent)
1887 0 7.50 3.9
1888 2.6 7.14 4.4
1889 5.6 7.71 5.0
1890 17.4 6.58 8.7
1891 50.0 4.58 36.4
1892 41.2 3.20 45.5
Note The years 1887-1892 span about 30
generations of parent x offspring and sib matings.
(After Lerner 1954. Data from Ritzema Bos)
Table 1
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Survivorship of Inbred and Noninbred Mice
The mouse population was sampled six times during
a 10-week period. Noninbred mice (red) had a
higher survivorship than inbred mice (blue).
Figure 18-2
(Adapted from Jiménez et al., Science, Vol.
266,14 Oct. 1994.)
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Stigma
Anther
Stamen
Filament
Carpel
Style
Pistil
Sepal
Ovary
Ovules
Structure of an angiosperm flower
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Pollen grain
Stigma
Figure 31.5. A pollination tube. This pollen
grain has successfully grown down the long stigma
to reach and fertilize the ovule.
Pollen tube
Carpel
Ovary
Ovule
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Stolons
New plant
Stolon (runner)
Adventitious roots
The strawberry reproduces asexually by forming
stolons, or runners.
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Stem, axillary buds, and terminal bud
Leaves
Vertical modular units
Flowers
Parent
Clones
Horizontal and vertical modular growth in an
aspen tree. (Populus tremuloides). Vertical
growth involves modules of leaves, buds, and
associated stems. Horizontal growth involves
modules of roots and root buds, which give rise
to clones. These clones are various age, with the
youngest individuals forming the leading edge of
growth away from the parent.
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30
25
10
20
8
Frequency of Fya (percent)
Frequency of admixture
15
6
10
4
5
2
0
Charleston, S. Carolina
Evans and Bullock Counties, S. Georgia
New York City
Oakland, California
Detroit, Michigan
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19
18
17
16
15
14
13
12
11
Percentage of oil
10
9
8
7
6
5
4
3
2
1
0
10
20
30
40
50
60
70
80
Generation
Selection for high and low oil content in corn
seed. The two lines pointing toward the center
indicate the results of selection in the reverse
direction started in generation 48. (Data from
J. W. Dudley, 1977. Proc. Int. Cong. Quant.
Genet. E. Pollak, O. Kempthorne, and T.B.
Bailey, eds., pages 459 ff.)
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Many Vegetables from One Species

European agriculturalists chose as parents for
subsequent generations individual wild mustard
plants that varied from the populations average
by producing unusually large leaves, stems, buds,
or flowers.
Brassica oleracea (A common wild mustard)
Selection for terminal buds
Selection for stems and flowers
Selection for flower clusters
Selection for leaves
Selection for stem
Selection for lateral buds
Cabbage
Brussels sprouts
Kohlrabi
Kale
Broccoli
Cauliflower
All of these crop plants have been derived from a
single wild mustard species. They illustrate the
vast amount of variation that can be present in a
gene pool.
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Rise of genetic resistance to pesticides, 1945-98
600
500
Gypsy moth caterpillar
Boll weevil
Insects and mites
400
300
Number of species
Plant diseases
200
Weeds
100
0
1950
1960
1970
1980
1990
2000
2010
Year
(Data from U.S. Department of Agriculture and the
Worldwide Institute)
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Average Dose Necessary to Kill Two Cotton Pests
Compound Average dose necessary to kill (milligrams per gram of larva) Average dose necessary to kill (milligrams per gram of larva) Average dose necessary to kill (milligrams per gram of larva) Average dose necessary to kill (milligrams per gram of larva)
Bollworm Bollworm Tobacco budworm Tobacco budworm
1960 1965 1961 1965
Strobane and DDT 0.03 1.000 0.13 16.51
Endrin 0.01 0.13 0.06 12.94
Carbaryl 0.12 0.54 0.30 54.57
Strobane and DDT 0.05 1.04 0.73 11.12
Toxaphine and DDT 0.04 0.46 0.47 3.52
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Three Modes of Natural Selection
Time 1
Time 2
Time
Time 3
Stabilizing Selection
Directional Selection
Disruptive Selection
Using the phenotypic variation of a small
population of butterflies as the example. The
bell-shaped curve represents the range of
continuous variation in wing color. The most
common forms (powder blue) are between extreme
forms of the trait (white at one end of the
curve, deep purple at the other). Orange arrows
signify which forms are being selected against
over time.
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The curve shows the relationship between the size
of eggs laid by pullets and the relative fitness
of the pullets as judged by the number of chicks
they produce on average.
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Birth Weight in Kilograms
1
2
3
4
5
20
100
70
50
15
30
20
Percent of Births in Population
Percent of Infant Mortality
10
10
7
5
5
3
2
1
2
3
4
5
6
7
8
9
10
11
Birth Weight in Pounds
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Comparison of Number of Released and Recaptured
Speckled versus Dark Peppered Moths in Polluted
and Pollution-Free Areas
Number Released
Number Recaptured
Speckled
Dark
Speckled
Dark
Location
Birmingham (polluted)
64
154
16 (25.0)
82 (53.2)
Dorset (pollution-free)
393
406
54 (13.7)
19 (4.7)
Percent recaptured is in parentheses.
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Geographic Variation in the Frequency of Melanic
Moths in the 1950s
Which reached as high as 100 in polluted
localities downwind from major industrial centers
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Clean Air and the Pepper Moth
300
Bishop Cook Wrexham West Kirby
250
200
Mean Winter SO2 (?g/m3)
150
100
50
0
1960
65
70
75
80
83
Years
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Selection Against Melanism
Source Data from Grant, et al., Parallel Rise
and Fall of Melanic Peppered Moths in Journal of
Heredity, vol. 87, 1996, Oxford University Press.
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Habitat Variation in Color and Striping Patterns
of European Garden Snails (Cepaea nemoralis)
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The Brain Race Coevolution of Brain Size in
Predator and Prey
Percent of Species
Recent
Percent of Species
20 million years ago
Percent of Species
60 million years ago
Small
Large
Relative Brain Size
As prey animals brain size expanded over 60
million years of evolution (green line), brain
size of their coevolving predators increased
accordingly (red line) and stayed slightly ahead.
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Occurrence of P. falciparum malaria
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SICKLE CELL HETEROZYGOTE ADVANTAGE 
1. A smaller percentage of heterozygotes are
infected with malaria than are normal
homozygotes   2. The parasite count in blood is
lower in heterozygotes than in normal
homozygotes.   3. The death rate in
heterozygotes is less than in normal homozygotes.
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Frequency of Alleles for Thalassemia (Actually
the sum for alleles that lead to several
different forms of Thalassemia)
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Frequency of Allele for G6PD Deficiency