biology chapter 16: 10th edition how populations evolve
TRANSCRIPT
![Page 1: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/1.jpg)
Sylv
ia S
. Ma
der
Copyright © The McGraw Hill Companies Inc. Permission required for reproduction or display
PowerPoint® Lecture Slides are prepared by Dr. Isaac Barjis, Biology Instructor
BIOLOGY 10th Edition
How Populations Evolve
Chapter 16: pp. 283 - 298
1
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
10% of
population
20% of
population
natural disaster kills
five green frogs
![Page 2: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/2.jpg)
2
Outline
Population genetics
Variations in terms of allele differences.
Microevolution
Hardy-Weinberg
Causes of Microevolution
Natural Selection
Types of Selection
Macroevolution
![Page 3: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/3.jpg)
3
Population Genetics
Population
All members of a single species
Occupying a particular area at the same time.
![Page 4: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/4.jpg)
4
HapMap Project
People inherit patterns of sequence differences, called haplotypes If one haplotype of a person has an A rather than a G at a
particular location in a chromosome, there are probably other particular base differences near the A
Genetic data from African, Asian, and European populations will be analyzed
A HapMap is a catalog common sequence differences that occur in a species The goal of the project is to link haplotypes to risk for specific
illnesses
May lead to new methods of preventing, diagnosing, and treating disease
![Page 5: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/5.jpg)
5
HapMap Project
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(Top left, center, right; Bottom 1, 3, 4): © Vol. 105/PhotoDisc/Getty; (Bottom 2): © Vol. 42/PhotoDisc/Getty; (Bottom 5): © Vol. 116/PhotoDisc/Getty
![Page 6: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/6.jpg)
6
Microevolution
In 1930s population geneticists described variations in a population in terms of alleles
Microevolution pertains to evolutionary changes within a population.
Various alleles at all the gene loci in all individuals make up the gene pool of the population.
Gene pool of a population: Genotype
Allele frequencies
![Page 7: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/7.jpg)
7
Frequency of Gametes Calculation
From genotype frequencies, the allele and
gamete frequencies can be calculated
frequency of genotypes
in the population 0.04
0.04 + 0.16 0.16 + 0.64
0.20 D 0.80 d
0.32 0.64
frequency of alleles and
gametes in the population
DD Dd dd
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
genotypes
![Page 8: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/8.jpg)
8
Hardy-Weinberg
The Hardy-Weinberg principle:
Allele frequencies in a population will remain
constant assuming:
No Mutations
No Gene Flow
Random Mating
No Genetic Drift
No Selection
![Page 9: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/9.jpg)
9
Hardy-Weinberg Equilibrium
eggs
sp
erm
Offspring
0.20 D 0.80 d
0.20 D
0.80 d
DD
0.04 DD 0.16 Dd
0.16 Dd 0.64 dd
Genotypes:
0.04
D = 0.20 d = 0.80
0.32 0.64 Genotype frequencies:
p2 + 2pq + q2 = 1
p2 = frequency of DD genotype (dark-colored) = (0.20)2 = 0.04
= 0.32
= 0.64
1.00
2pq = frequency of Dd genotype (dark-colored) = 2(0.20)(0.80)
q2 = frequency of dd genotype (light-colored) = (0.80)2
Allele and gamete frequencies:
F 1 generation
F 2 generation
Genotype frequencies: 0.04 DD + 0.32 Dd + 0.64 dd = 1
Dd dd
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
![Page 10: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/10.jpg)
10
Industrial Melanism and Microevolution
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Early observation Later observation
36% dark-colored phenotype 64% dark-colored phenotype
![Page 11: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/11.jpg)
11
Hardy-Weinberg
Required conditions are rarely (if ever) met
Changes in gene pool frequencies are likely
When gene pool frequencies change, microevolution
has occurred
Deviations from a Hardy-Weinberg equilibrium
indicate that evolution has taken place
![Page 12: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/12.jpg)
12
Causes of Microevolution
Genetic Mutations
The raw material for evolutionary change
Provides new combinations of alleles
Some might be more adaptive than others
![Page 13: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/13.jpg)
13
Causes of Microevolution
Gene Flow
Movement of alleles between populations
when:
Gametes or seeds (in plants) are carried into
another population
Breeding individuals migrate into or out of
population
Continual gene flow reduces genetic
divergence between populations
![Page 14: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/14.jpg)
14
Gene Flow
stigma
self-
pollination
stamen
Pisum sativum
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
![Page 15: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/15.jpg)
15
Causes of Microevolution
Nonrandom Mating
When individuals do not choose mates randomly
Assortative mating:
Individuals select mates with their phenotype
Individuals reject mates with differing phenotype
Sexual selection:
Males compete for the right to reproduce
Females choose with males possessing a particular phenotype
Both of these cause an increase in homozygotes
![Page 16: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/16.jpg)
16
Causes of Microevolution
Genetic Drift
Occurs by disproportionate random sampling from
population
Can cause the gene pools of two isolated populations to become
dissimilar
Some alleles are lost and others become fixed (unopposed)
Likely to occur:
After a bottleneck
When severe inbreeding occurs, or
When founders start a new population
Stronger effect in small populations
![Page 17: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/17.jpg)
17
Genetic Drift
natural disaster kills
five green frogs
20% of
population
10% of
population
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
![Page 18: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/18.jpg)
18
Genetic Drift
Bottleneck Effect
A random event prevents a majority of
individuals from entering the next generation
Next generation composed of alleles that just
happened to make it
![Page 19: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/19.jpg)
19
Genetic Drift
Founder Effect
When a new population is started from just a few individuals
The alleles carried by population founders are dictated by chance
Formerly rare alleles will either:
Occur at a higher frequency in the new population, or
Be absent in new population
![Page 20: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/20.jpg)
Animation
20
Please note that due to differing
operating systems, some animations
will not appear until the presentation is
viewed in Presentation Mode (Slide
Show view). You may see blank slides
in the “Normal” or “Slide Sorter” views.
All animations will appear after viewing
in Presentation Mode and playing each
animation. Most animations will require
the latest version of the Flash Player,
which is available at
http://get.adobe.com/flashplayer.
![Page 21: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/21.jpg)
21
Founder Effect
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Courtesy Victor McKusick
![Page 22: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/22.jpg)
22
Natural Selection
Adaptation of a population to the biotic and
abiotic environment
Requires:
Variation - The members of a population differ from
one another
Inheritance - Many differences are heritable genetic
differences
Differential Adaptiveness - Some differences affect
survivability
Differential Reproduction – Some differences affect
likelihood of successful reproduction
![Page 23: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/23.jpg)
23
Natural Selection
Results in:
A change in allele frequencies of the gene pool
Improved fitness of the population
Major cause of microevolution
![Page 24: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/24.jpg)
24
Types of Selection
Most traits are polygenic - variations in the trait
result in a bell-shaped curve
Three types of selection occur:
(1) Directional Selection
The curve shifts in one direction
Bacteria become resistant to antibiotics
Guppies become more colorful in the absence of predation
![Page 25: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/25.jpg)
25
Three Type of Natural Selection
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Nu
mb
er
of
Ind
ivid
ua
ls
Nu
mb
er
of
Ind
ivid
ua
ls
stabilizing selection
a. b. c.
Peak narrows.
disruptive selection
Two peaks result.
directional selection
Peak shifts.
Phenotype Range Phenotype Range Phenotype Range
![Page 26: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/26.jpg)
26
Directional Selection
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Am
ou
nt
of
Co
lor
Low
predation
No
predation All guppies
are drab
and small
High
predation
0 12 8 4 Months
Experimental site Result
above waterfall
below waterfall
© Helen Rodd
![Page 27: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/27.jpg)
27
Types of Selection
Three types of selection occur (cont):
(2) Stabilizing Selection
The peak of the curve increases and tails decrease
Ex - when human babies with low or high birth
weight are less likely to survive
(3) Disruptive
The curve has two peaks
Ex – When Cepaea snails vary because a wide
geographic range causes selection to vary
![Page 28: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/28.jpg)
28
Stabilizing Selection
Due to stabilizing selection, the average
human birth weight stays steady. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Pe
rce
nt
of
Bir
ths in
Po
pu
lati
on
P
erc
en
t Infa
nt M
orta
lity
20
15
10
5
10
20
30
50
70
100
5
7
3 2
.9 1.4 1.8 2.3 2.7 Birth Weight (in kilograms)
3.2 3.6 4.1 4.5
![Page 29: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/29.jpg)
29
Disruptive Selection
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
© Bob Evans/Peter Arnold, Inc.
Forested
areas
Low-lying
vegetatio
![Page 30: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/30.jpg)
30
Sexual Selection
Female Choice
Choice of a mate is serious consideration
Good genes hypothesis: Females choose mates on the basis
of traits that improve the chance of survival.
Runaway hypothesis: Females choose mates on the basis of
traits that improve male appearance.
Male Competition
Can father many offspring because they continuously
produce sperm in great quantity.
Compete to inseminate as many females as possible.
![Page 31: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/31.jpg)
31
Sexual Selection
Sexual selection adaptive changes in
males and females to increase ability to
secure a mate.
Males - ability to compete
Females choose to select a male with the best
fitness (ability to produce surviving offspring).
![Page 32: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/32.jpg)
32
Sexual Selection
The drab
females tend to
choose
flamboyant
males as
mates.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
![Page 33: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/33.jpg)
33
Sexual Selection: Competition
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a: © Y. Arthus-Bertrand/Peter Arnold, Inc.; b: © Neil McIntre/Getty Images
b.
a.
![Page 34: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/34.jpg)
34
Sexual Selection: Competition
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
© Barbara Gerlach/Visuals Unlimited
![Page 35: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/35.jpg)
35
Sexual Selection in Humans
Study shows that female choice and male competition apply to humans too
Women must invest more in having a child than men.
Men, need only contribute sperm Generally more available for mating than are
women.
More men = competition
Men Also Have a Choice Prefer women who are most likely to present them
with children.
![Page 36: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/36.jpg)
36
King Husain and Family
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
© Jodi Cobb/National Geographic Image Collection
![Page 37: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/37.jpg)
37
Maintenance of Variations
Genetic variability
Populations with limited variation may not be
able to adapt to new conditions
Maintenance of variability is advantageous to
population
Only exposed alleles are subject to natural
selection
![Page 38: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/38.jpg)
38
Maintenance of Variations
Recessive alleles:
Heterozygotes shelter recessive alleles from selection
Allows even lethal alleles to remain in population at low
frequencies virtually forever
Lethal recessive alleles may confer advantage to
heterozygotes
Sickle cell anemia is detrimental in homozygote
However, heterozygotes more likely to survive malaria
Sickle cell allele occurs at higher than expected frequency in
malaria prone areas
![Page 39: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/39.jpg)
39
Subspecies
Pantheropsis obsoleta lindheimeri Pantheropsis obsoleta rossalleni Pantheropsis obsoleta spiloides
Pantheropsis obsoleta quadrivittata
Pantheropsis obsoleta obsoleta
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
(E.o. lindheimeri, E.o. quadrivittata): © Zig Leszczynski/Animals Animals/Earth Scenes; (E.o. spiloides): © Joseph Collins/Photo Researchers, Inc.;
(E.o. rossalleni): © Dale Jackson/Visuals Unlimited; (E.o. obsoleta): © William Weber/Visuals Unlimited.
![Page 40: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/40.jpg)
40
Species Definitions
Species Definitions
Morphological
Can be distinguished anatomically
Specialist decides what criteria probably represent
reproductively isolated populations
Most species described this way
![Page 41: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/41.jpg)
41
Species Definitions
Species Definitions
Biological
Populations of the same species breed only among
themselves
Are reproductively isolated from other such
populations
Very few actually tested for reproductive isolation
![Page 42: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/42.jpg)
42
Heterozygote Advantage
Assists the maintenance of genetic, and
therefore phenotypic, variations in future
generations.
In sickle cell disease heterozygous
individuals don’t die from sickle-cell
disease, and they don’t die from malaria.
![Page 43: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/43.jpg)
43
Sickle Cell Disease
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
sickle-cell
overlap of both
malaria
![Page 44: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/44.jpg)
44
Review
Microevolution
Hardy-Weinberg
Causes of Microevolution
Natural Selection
Types of Selection
Macroevolution
![Page 45: BIOLOGY Chapter 16: 10th Edition How Populations Evolve](https://reader034.vdocuments.us/reader034/viewer/2022052023/6286cd853473af26684359a0/html5/thumbnails/45.jpg)
Sylv
ia S
. Ma
der
Copyright © The McGraw Hill Companies Inc. Permission required for reproduction or display
PowerPoint® Lecture Slides are prepared by Dr. Isaac Barjis, Biology Instructor
BIOLOGY 10th Edition
How Populations Evolve
Chapter 16: pp. 283 - 298
45
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
10% of
population
20% of
population
natural disaster kills
five green frogs