EVOLUTION
Regents Biology
OBJECTIVES
Upon completion of this unit students will be able to:
1. Describe 5 processes by which fossils may be formed.
2. Explain why fossils are often found in sedimentary rocks.
3. Differentiate relative and absolute dating.
4. Explain how radioactive dating can determine the age of rocks.
5. Define the terms correlation and index fossil.
6. Explain what is meant by the geologic time scale.
7. State two important conclusions that can be drawn from the fossil record regarding the
course of changes in living things over geologic time.
8. Explain the importance of extinctions.
9. Differentiate analogous, homologous, and vestigial structures.
10. Explain how similarities in biochemistry, anatomy, and embryonic development show
an evolutionary relationship between different species.
11. Describe spontaneous generation.
12. Explain how Redi initially disproved spontaneous generation.
13. Explain how Spallanzani’s and Pasteur’s experiments finally disproved spontaneous
generation.
14. Describe the conditions thought to have existed on the primitive earth according to the
heterotroph hypothesis, and experiments supporting it.
15. Outline Lamarck’s theory of evolution and describe how Weismann’s experiment disproved it.
16. Explain the principle of natural selection and give examples
17. List the six main points of Darwin’s theory of evolution and state the weaknesses to his theory.
18. Differentiate gradualism and punctuated equilibrium.
19. List the causes of genetic variation in a species.
20. Explain what an adaptation is and give examples.
21. Describe different types of speciation.
KEY WORDS
1.
2.
3.
4.
5.
6.
7.
adaptation
correlation
fossil
fossil record
gene pool
geologic evolution
gradualism
8. index fossil
9. natural selection
10. organic evolution
11. population genetics
12. punctuated
equilibrium
13. speciation
14. taxonomy
EVIDENCE OF EVOLUTION
•Evolution: GRADUAL CHANGE
FROM ONE STATE TO ANOTHER
•Geologic evolution: CONTINUAL
CHANGE OF THE EARTH (4.5 BYA)
•Organic evolution: CONTINUAL
CHANGE OF LIVING THINGS
I. FOSSILS
• Fossil: REMAINS/TRACE OF AN ORGANISM;
STRONGEST EVIDENCE OF ORGANIC
EVOLUTION
• Types of fossil formation:
1. Preservation in amber – TRAPPED/EMBEDDED
IN RESIN
2. Preservation in ice – FROZEN REMAINS
3. Preserved hard parts - BONES
4. Petrifaction – REMAINS TURN TO STONE
5. Molds and Casts - MOLD = SHAPE
PRESERVED (HOLLOW); CAST = MOLD FILLS
WITH MINERALS (SOLID)
6. Imprints – IMPRESSION THAT HARDENS
http://images.google.com/imgres?imgurl=http://www.abc.net.au/beasts/evidence/prog1/images/evi
_fossil1_large.jpg&imgrefurl=http://www.abc.net.au/beasts/evidence/prog1/page1.htm&h=315&w=
400&sz=19&hl=en&start=8&tbnid=pqgQLZ5NgVuokM:&tbnh=98&tbnw=124&prev=/images%3Fq
%3DFOSSIL%26gbv%3D2%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:enUS:official%26sa%3DG
http://images.google.com/imgres?imgurl=http://news.nationalgeographic.com/news/2007/08/images/070816-fossil-spider_big.jpg&imgrefurl=http://news.nationalgeographic.com/news/2007/08/070816-fossilspider.html&h=439&w=461&sz=61&hl=en&start=6&tbnid=vP3dG-jNw_NL2M:&tbnh=122&tbnw=128&prev=/images%3Fq%3DFOSSIL%26gbv%3D2%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26sa%3DG
II. SEDIMENTARY ROCKS
• The YOUNGEST layer is always found at the TOP:
http://stloe.most.go.th/html/lo_index/LOcanada2/206/images/2_6_1en.jpg
http://www.moorlandschool.co.uk/earth/earth_science/utah_sandstone.jpg
• Layers of sedimentary rock that contain FOSSILS tell us about what
existed at a particular PLACE and TIME
III. THE FOSSIL RECORD: HISTORY OF LIFE
A) Relative Dating – DETERMINING THE ORDER OF EVENTS
http://facweb.bhc.edu/academics/science/harwoodr/Geol101/labs/Dating2/Images/relative02.gif
B) Correlation – MATCHING LAYERS TO DO RELATIVE
DATING (MATCHING AGES OF ROCK THAT ARE CLOSE IN
PROXIMITY)
http://stloe.most.go.th/html/lo_index/LOcanada8/802/images/eng/1_2.jpg
C) Index fossils – RELATIVE DATING OF ROCKS WITHIN A
NARROW TIME FRAME; MATCHING RELATIVE AGES OF
SEDIMENTARY ROCK AT VERY DIFFERENT PLACES)
http://www.adrian.edu/chemistry/th/Somelinks/Spages/ttackett/fossils.gif
D) Characteristics of the Fossil Record
1. The earliest organisms were relatively SIMPLE
2. There is a GRADUAL transition from EARLIER forms to
LATER
forms
Later forms developed from
early forms by a series of
changes passed on from
generation to generation;
there are “missing links”
(a.k.a. TRANSITIONAL FORMS)
IV. ABSOLUTE DATING
• Tells us the ACTUAL age of something
• RADIOACTIVE DATING is the most accurate and reliable
method (igneous rocks only)
http://evolution.berkeley.edu/evosite/lines/images/strat_column.gif
V. GEOLOGIC TIME SCALE
• Time table of
the earth’s history
• Each ERA is divided
into PERIODS
(epochs)
VI. OTHER EVIDENCE OF EVOLUTION
A) Comparative Anatomy – STUDY OF STRUCTURAL
SIMILARITIES AND DIFFERENCES AMONG LIVING THINGS
•
Similar anatomies provide evidence about EVOLUTIONARY
RELATIONSHIPS between organisms
Http://www.talkorigins.org/faqs/homs/pelvis.jpg
•
Homologous structures are parts on DIFFERENT organisms
that have similar STRUCTURE but different FUNCTION; this
shows evolution along the SAME LINES
EXAMPLES: hand of a human, flipper of a whale, front leg of cat,
wing of bat, wing of bird
HOMOLOGOUS STRUCTURES
(SIMILAR STRUCTURE, DIFFERENT FUNCTION)
•Analogous structures are parts on DIFFERENT organisms that
have different STRUCTURE but similar FUNCTION ; this shows
evidence of evolution along DIFFERENT LINES
EXAMPLES: wing of a bird, wing of an insect
http://www.bio.miami.edu/dana/pix/analogous.gif
•Vestigial structures are the remnants of structures that were once
FUNCTIONAL in our ancestors, but now are SMALLER and serve
little or no function
EXAMPLES: human coccyx, appendix, wisdom teeth, muscles that
move the nose and ears
http://content.answers.com/main/content/wp/en/thumb/f/f0/250px-Eye_0012.jpg
http://images.google.com/imgres?imgurl=http://content.answers.com/main/conte
nt/wp/en/5/5f/Chickenblinking.jpg&imgrefurl=http://www.answers.com/topic/nictit
atingmembrane&h=199&w=252&sz=42&hl=en&start=16&tbnid=xFyFBUQLqcmtmM:
&tbnh=88&tbnw=111&prev=/images%3Fq%3Dnictitating%2Bmembrane%2Bhu
man%26gbv%3D2%26ndsp%3D20%26hl%3Den%26client%3Dfirefoxa%26rls%3Dorg.mozilla:en-US:official%26sa%3DN
B) Comparative Embryology
• Similarities in embryonic development supports the idea that
CERTAIN ORGANISMS HAVE A COMMON EVOLUTIONARY ORIGIN
• The more two organisms resemble each
other as adults, the
MORE CLOSELY
RELATED THEY ARE
(EXAMPLE: humans and chimps)
http://www.terradaily.com/images/human-chimp-anatomy-comparison-bg.jpg
C) Comparative Biochemistry and Immunology
• The closer the evolutionary relationship between two organisms,
the more alike their structure of THEIR DNA and PROTEIN
MOLECULES
EXAMPLE: the hemoglobin of humans and gorillas is the same
except for one amino acid!
http://www.bloodless.it/hemoglobin.jpg
VII. THEORIES OF EVOLUTION
A) Lamarck
o Was a scientist who believed that evolutionary changes
were caused by the need to ADAPT TO THE
ENVIRONMENT
o He came up with two principles:
1.
The Law of Use and Disuse
• The more something is used, the STRONGER its
development
• The less something is used, the WEAKER its
development
2.
Inheritance of Acquired Characteristics
• Characteristics of an organism developed through USE
AND DISUSE could be passed on to OFFSPRING
EXAMPLE: neck of a giraffe
(see figure on next page)
B) Weismann
 Disproved Lamarck’s theory
 Hypothesized that traits are passed on to offspring by GENES,
not life experiences
 He cut the tails off of mice for 22 generations; all of the new
mice had normal tails; therefore tail length is not INHERITED
http://www.bbc.co.uk/manchester/content/images/2005/09/01/rebecca_mcevoy_mouse_tail_203x152.jpg
C) Charles Darwin
 Darwin observed many species during his travels, namely
at the GALAPAGOS ISLANDS
 Some observations he made while traveling:
1. There seemed to be a GRADUAL change in species as
he moved down the coast of SOUTH AMERICA
2. Fossils that he found were unlike anything he had seen;
were they related to modern forms?
http://www.ecuador.us/images/mapgalap.gif
3. The finches (type of bird) on the Galapagos Islands appeared
different due to ISOLATION AND ADAPTATION
D) Darwin’s Theory of Evolution
• Darwin’s theory was composed of several ideas:
1. Overproduction: SPECIES POPULATIONS REMAIN
CONSTANT; ALL OFFSPRING DOES NOT REPRODUCE
2. Struggle for Existence: SPACE AND FOOD ARE LIMITED, SO
THERE IS COMPETITION
3. Variation: DIFFERENCES BETWEEN INDIVIDUALS (SOME
MORE IMPORTANT THAN OTHERS)
4. Survival of the Fittest: SOME INDIVIDUALS ARE BETTER
EQUIPPED THAN OTHERS TO SURVIVE AND REPRODUCE
(ADAPT BETTER TO THE ENVIRONMENT)
5. Natural Selection: ORGANISMS WITH FAVORABLE
VARIATIONS ARE ABLE TO SURVIVE AND REPRODUCE
BETTER THAN ORGANISMS WITH UNFAVORABLE
CHARACTERISTICS; CAN RESULT IN NEW SPECIES
6. Evolution of New Species: OVER TIME, THE FAVORABLE
CHANGES BECOME SO GREAT THAT THE NET RESULT IS
A NEW SPECIES
http://www.globalchange.umich.edu/globalchange1/current/lectures/selection/boxes.gif
• WEAKNESSES to Darwin’s theory:
1. Does not explain the ORIGIN and
transmissions of VARIATIONS
2. Variations caused by
HEREDITARY DIFFERENCES vs.
those caused by THE
ENVIRONMENT (NOT INHERITED)
E) Rate of Evolution
•The rate of evolution, or HOW FAST/SLOW IT OCCURS,
is not agreed upon. There are two “camps” within the
scientific community (Gradualism vs. Punctuated
Equilibrium):
GRADUALISM
PUNCTUATED EQUILIBRIUM
· DARWIN
· GOULD & ELDEREDGE
· EVOLUTION OCCURS
SLOWLY AND GRADUALLY
· PERIODS OF EQUILIBRIUM
ARE INTERRUPTED BY A
SHORT PERIOD OF RAPID
EVOLUTION
F) Synthetic Theory of Evolution
• Scientists that back this theory believe that
evolution happens to POPULATIONS, not
INDIVIDUALS
• INDIVIDUALS are the units of natural
selection
• Evolution is a change in ALLELE
FREQUENCY within a population over a
period of time
VIII. DEVRIES AND THE MUTATION
THEORY
• Devries added MUTATION to
Darwin’s theory
• He claimed that changes leading to
new species occurred in SUDDEN,
LARGE changes in heredity resulting
from MUTATION, NOT slowly over
time
EXAMPLE: the giraffe with the long neck
was from a mutation; the environment
changed and the long neck was
advantageous, and this species survived
IX. SOURCES OF VARIATION
A) Gene mutations
• Gene mutation are the MAJOR source of variation
• Mutations of particular genes are RARE, but among thousands, at
least ONE gene is mutated
• Most gene mutations are RECESSIVE (PKU, white-eyed fly, etc.)
B) Chromosomal mutations
• Does not produce new GENES, but results in new
COMBINATIONS of genes in the organism (Down Syndrome, etc.).
C) Recombination
• New combinations of alleles from:
1. MEIOSIS (crossing-over, independent assortment)
2. FERTILIZATION
D) Immigration and Emigration
• Immigration: INDIVIDUALS MOVING INTO A POPULATION,
BRINGING GENES NOT ALREADY PRESENT
• Emigration: INDIVIDUALS LEAVING A POPULATION,
X. POPULATION GENETICS
• Population: ORGANISMS OF THE SAME SPECIES LIVING
TOGETHER AND ARE CAPABLE OF INTERBREEDING
• The genetic makeup of a population changes from GENERATION
to GENERATION (it evolves)
• As individuals reproduce and die, the GENETIC MAKEUP of a
population changes
XI. ALLELE FREQUENCIES
• Each individual of a population has a set of ALLELES that is not
the same as any other individual, although individuals do have many
of the same ALLELES
• Total alleles in a population is known as theGENE POOL
• Each allele occurs in the gene pool with a certain FREQUENCY
(100%0%)
• As time goes on, the allele frequency in the gene pool may change
as a result of NATURAL SELECTION
• Evolution: GRADUAL CHANGE OF ALLELE FREQUENCY IN A
POPULATION
XII. DIFFERENTIAL REPRODUCTION
• MUTATIONS  NEW ALLELES  VARIATION
• Individuals with favorable variations will survive LONGER
(natural selection)
Certain allele frequencies will increase
(FAVORABLE) and others will decrease
(UNFAVORABLE)
EXAMPLE: In the original giraffe population, the alleles for
the long neck were at a LOW frequency; the change in the
environment caused the alleles for the long neck to be at a
HIGH frequency (eventually 100% frequency)
XIII. THE HARDY WEINBERG-LAW
• EXAMPLE: allele for white eye = 90% frequency; allele for red eye
= 10% frequency
Question: What will happen to these frequencies as time goes on?
Will white eyes replace red eyes so that white eyes = 100%
frequency?
If all of these happen,
there will be no change in
allele frequency
Answer: NO !!!! Sexual reproduction alone cannot change allele
frequency (this is known as the HARDY-WEINBERG LAW)
• Requirements for the Hardy-Weinberg Law:
1.
LARGE POPULATION
2.
NO MIGRATION
3.
NO MUTATIONS
4.
RANDOM REPRODIUCTION
• What’s the point? To show that EVOLUTION IS OCCURING and
that the ALLELE FREQUENCIES ARE CHANGING
XIV. ADAPTATIONS
• Adaptation: INHERITED TRAIT THAT IMPROVES AN
ORGANISMS’ CHANCE OF SURVIVAL AND REPRODUCTION
• Adaptations can be STRUCTURAL or PHYSIOLOGICAL
EXAMPLES: camouflage (blending), warning coloration (easier to
see), mimicry (resembling something else)
http://3quarksdaily.blogs.com/3quarksdaily/images/wolfe_seal_1.jpg
http://xnet.rrc.mb.ca/davidb/laselva62_jpg_jpg.jpg
http://xnet.rrc.mb.ca/davidb/laselva62_jpg_jpg.jpg
XV. SPECIATION
A) Geography
• Range :EACH
SPECIES FOUND IN A
REGION
• Characteristics of
species are often
different in different
parts of its RANGE
• Sometimes when
species are separated,
they cannot
INTERBREED and a
new species develops
http://bio.research.ucsc.edu/~barrylab/classes/animal_behavior/IMAGES4.DIR/SPECMODE.GIF
B) Types of Speciation
1.
ISOLATION – NO INTERBREEDING WITHIN A SPECIES
• Geographic isolation – NATURAL BARRIERS (ISLANDS,
MOUNTAINS, ETC.)
• Reproductive isolation – MATING BARRIERS (COURTSHIP
BEHAVIOR, MATING TIMES)
2.
POLYPLOIDY – 3n, 4n, 5n # OF CHROMOSOMES
• These offspring can interbreed only among THEMSELVES
3.
ADAPTIVE RADIATION – ANCESTOR EVOLVES INTO
SEVERAL DIFFERENT SPECIES, EACH IN A DIFFERENT
HABITAT (DARWIN’S FINCHES)
4.
CONVERGENT EVOLUTION – UNRELATED SPECIES
RESEMBLE EACH OTHER DUE TO NATURAL SELECTION
(SIMILAR ADAPTATIONS)
EXAMPLE: marsupial mouse – rodent
Tasmanian wolf – wolf
Koala bear – bear
All have similar
needs in similar
environments
Speciation by Isolation
http://www.pandasthumb.org/pt-archives/allopatry.jpg
Speciation by Adaptive Radiation
http://images.google.com/imgres?imgurl=http://www.pbs.org/wgbh/evolution/library/01/6/images/l_016_02_l.gif&imgrefurl=http://www.pbs.org/wgbh/evolution/library/01/6/image_pop/l_016_02.html&h=284&w=500&sz=30&hl=en&start=10&sig2=CWbxl3ByJaztcdFZt5ZYrA&tbnid=0o6VftBvCEqrM:&tbnh=74&tbnw=130&ei=ZVU9SK6RHoSYeoHC8LIO&prev=/images%3Fq%3Ddarwin%2527s%2Bfinches%26gbv%3D2%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26sa%3DG
Speciation by Polyploidy
http://polyploid.agronomy.wisc.edu/overview/Slide2.gif
Speciation by Convergent Evolution
http://www.freewebs.com/carakiller/convergent%20evolution.jpg
A) BACTERIAL RESISITANCE TO ANTIBIOTICS
• Antibiotics kill BACTERIA
• Resistant strains of bacteria appeared due to FREQUENT USE
• Antibiotics are no longer effective in killing certain strains:
•In large populations of bacteria, some individuals have what is
called RESISTANCE to an antibiotic (resistance is a genetic
trait)
•In an environment containing the ANTIBIOTIC, only the
resistant STRAINS will grow and reproduce
•By NATURAL SELECTION, the strain with resistance
becomes the common type
A pure culture of bacteria can be tested for antibiotic
resistance by evenly swabbing it over an agar plate
and pressing discs of antibiotic into the agar. After a
period of incubation, sensitivity or resistance to the
antibiotic can be determined by measuring the zone
that forms around the disc. Large zones mean the
bacteria are sensitive to the drug, small or
nonexistent zones are signs of resistance. Image
Courtesy: Centers for Disease Control and
Prevention.
http://images.google.com/imgres?imgurl=http://www.jyi.org/articleimages/555/originals/img0.jpg&imgrefurl=http://www.jyi.org/news/nb.php%3Fid%3D555&h=291&w=433&sz=20&hl=en&start=5&sig2=MFLMVTtac5VUHcWYevo5Wg&um=1&tbnid=faRxqUHFSJZ0M:&tbnh=85&tbnw=126&ei=fX49SN-YGabaeoGDjKwO&prev=/images%3Fq%3Dantibiotic%2Bresistant%2Bbacteria%26um%3D1%26hl%3Den%26client%3Dfirefox-a%26channel%3Ds%26rls%3Dorg.mozilla:en-US:official%26sa%3DN
http://biopsy.files.wordpress.com/2008/04/antibiotic-resistance.jpg
B) INSECT RESISITANCE TO DDT
• DDT kills insects
• Some insects have a natural RESISTANCE to DDT
• DDT-sensitive insects get KILLED when exposed to DDT
• DDT-resistant insects SURVIVE and multiply by NATURAL
SELECTION
• Eventually, many insects will be RESISTANT to DDT
Diamondback
moth resistance
to insecticide in
Georgia
http://pubs.caes.uga.edu/caespubs/pubcd/C899-graphics/C899-cover.jpg
XVII. EARLY BELIEFS ABOUT THE ORIGIN OF LIFE
A) EARLY OBSERVATIONS
•Many believed that living organisms could arise spontaneously
from nonliving matter, this is called SPONTANEOUS
GENERATION
http://www.crystalinks.com/egyptplant.gif
B) Redi and maggots
• Redi disproved the idea of SPONTANEOUS GENERATION
• Common observation: when meat is exposed to the air,
MAGGOTS appear
• Many people thought that the maggots were formed from the
meat; but this is WRONG!
• Redi concluded that maggots did not arise spontaneously from
decaying meat, but from EGGS LAID BY FLIES
C) Boiled Soup
1.
Needham – reinforced belief in SPONTANEOUS GENERATION
o Boiled broth to kill MICROORGANISMS
o Microorganisms didn’t DIE
2.
Spallanzani – disproved Needham
o “Hey---Paisan---you didn’t heat the broth long to enough to KILL
THE BACTERIA!!!”
3.
Pasteur – Finalized that there is no SPONTANEOUS
GENERATION
o Microorganisms and their spores are present in the AIR
o They become active and reproduce in the BROTH
XVIII. MODERN THEORY ON THE ORIGIN OF LIFE
The Heterotroph Hypothesis (A. I. Oparin)
• The heterotroph hypothesis assumes that the world was once
different:
THEN
· HYDROGEN, WATER,
AMMONIA, METHANE IN
ATOMOSPHERE
· TEMPERATURE
RELATIVELY HIGH
· OCEANS HOT
NOW
· NITROGEN, OXYGEN,
CARBON DIOXIDE IN
ATMOSPHERE
· TEMPERATURE
“NORMAL”
· OCEANS NOT HOT
• The primitive atmosphere promoted chemical reactions, which
led to the synthesis of ORGANIC COMPOUNDS (radiation,
electric energy, X-rays, etc. all give off energy!)
• Miller later demonstrated that this could happen in a lab:
http://www.kennislink.nl/upload/150080_962_1144771463083-oersoepexperimentMiller.jpg
COACERVATES
(clusters of protein)
Absorbing material from environment (heterotrophs)
COACERVATES GROW &
REPRODUCE
Supply of materials decreased
COMPETITION AMONG
HETEROTROPHS
Favorable adaptations survived
PHOTOSYNTHETIC
ORGANISMS
(USE LIGHT FOR ATP)
Give off oxygen
MORE OXYGEN IN
THE AIR
Aerobic respiration favored
AEROBIC
ORGANISMS
DOMINANT
•The earth’s environment was completely altered
(old conditions were DESTROYED)