SlideShare a Scribd company logo
Chapter 17:
The Evolution of Life
Principles of Science II
This lecture will help you understand:
• The Origin of Life
• Did Life on Earth Originate on Mars?
• Early Life on Earth
• Charles Darwin and The Origin of Species
• How Natural Selection Works
• Adaptation
• Staying Warm and Keeping Cool
• Evolution and Genetics
• How Species Form
• Evidence of Evolution
• Fossils: Earth's Tangible Evidence of Evolution
• The Evolution of Humans
• History of Science: The Peppered Moth
• Science and Society: Antibiotic-Resistant Bacteria
The Origin of Life
• For thousands of years, people believed that life
was created through spontaneous generation, the
sudden emergence of living organisms from
nonliving materials.
The Origin of Life
• Louis Pasteur demonstrated that life did not arise
from nonlife.
The Origin of Life
• Life originated billions of years ago on a young
Earth very different from the Earth of today.
• The Miller and Urey experiment modeled the young
Earth's atmosphere and
oceans.
• When Miller and Urey shot
electric sparks through the model
to simulate lightning, complex
organic molecules formed.
The Origin of Life
• There are two alternative hypotheses for the origin
of organic molecules on Earth:
– Organic molecules came to Earth on incoming
meteorites.
– Organic molecules were synthesized in deep-
sea environments.
• But, how do you get from organic molecules to
cells?
The Origin of Life
• Liposomes form spontaneously when certain lipids
are added to water. Liposomes
– have double membranes similar to cell
membranes.
– can grow, shrink, and divide.
– run chemical reactions
inside their membranes.
– control what molecules
move into and out of them.
The Origin of Life
• Living cells also need genes.
• Scientists now believe that the first genes were
made of RNA, not DNA.
– Short strands of RNA can spontaneously
assemble from individual RNA nucleotides.
– RNA can replicate by itself.
• Liposomes may have captured RNA "genes,"
forming the first primitive cells on Earth.
Did Life on Earth Originate on Mars?
• In 1996, scientists found what resembled tiny,
fossilized bacteria in a Martian meteorite.
• Mars was once a much warmer and wetter planet.
• The supposed fossils may be too small to be
fossilized bacteria.
• NASA continues to explore the possibility of life on
Mars.
Early Life on Earth
• The origin of autotrophs
– Earth's earliest living organisms
• were marine prokaryotes.
• lived with no free oxygen.
• were heterotrophs that obtained energy and food from
outside sources.
– The evolution of autotrophs, organisms able to
convert inorganic molecules into food and organic
molecules, was a key event in the history of life.
• Photosynthesizers use energy from the Sun.
• Chemoautotrophs use energy from certain inorganic
chemicals.
Early Life on Earth
• The oxygenation of the atmosphere
– Cyanobacteria are photosynthetic bacteria that
produce oxygen as a by-product of
photosynthesis.
Early Life on Earth
• The first eukaryotes
– Eukaryotes appeared about 2 billion years ago.
– The nucleus and most organelles most likely
originated from inward foldings of the cell membrane.
– According to the endosymbiotic theory, mitochondria
and chloroplasts evolved from prokaryotes living
inside the earliest eukaryotic cells.
Charles Darwin and The Origin of Species
• For thousands of years, people believed that
species on Earth did not change.
• But then what are fossils?
Charles Darwin and The Origin of Species
• Jean Baptiste Lamarck argued that modern species
were descended from ancestors that had evolved to
become better adapted to their environments.
• Lamarck believed
that organisms
acquired new traits
over their lifetimes
and then passed
these traits to their
offspring. He called
this the inheritance
of acquired characteristics.
Charles Darwin and The Origin of Species
• Charles Darwin argued that evolution—inherited
changes in populations of organisms over time—
had produced all the living forms on Earth.
Charles Darwin and The Origin of Species
• Darwin was inspired by the observations he made as the
naturalist aboard the H.M.S. Beagle as it sailed around
South America from 1831 to 1836.
• For example, the 13 species of finches on the
Galápagos Islands varied in beak size and shape,
depending on their diet. How had the beaks of the
finches come to vary in this way?
Charles Darwin and The Origin of Species
• Darwin was also inspired by
– the work of geologist Charles Lyell, who argued
that Earth's geologic features were built by
gradual processes over millennia.
– the work of economist Thomas Malthus, who
wrote about famine and the struggle of humans
over resources.
How Natural Selection Works
• In any population of organisms, individuals have
many traits that show variation.
• Traits that are determined at least partly by genes
are heritable, passed from parents to offspring.
• Organisms that possess variable heritable traits that
are advantageous leave more offspring than
organisms without the advantageous traits. This is
natural selection.
• Advantageous traits become more common in a
population, resulting in adaptation.
How Natural Selection Works
Adaptation
• Adaptations are traits that make organisms well
suited to living and reproducing in their
environments.
• Adaptations can relate to various aspects of an
organism's life:
– Survival adaptations
– Sexual selection, which leads to the evolution of
adaptations that help organisms acquire mates
– Bearing and raising young
Staying Warm and Keeping Cool
• Mammals thermoregulate, maintaining
a fairly constant body temperature.
• The surface-area-to-volume ratio is an
important factor in thermoregulation.
It affects the size and shape of animals.
– Size: Animals found in cold habitats
are often larger than related species
living in warm habitats.
– Shape: Animals found in cold
habitats tend to have short legs and
small ears. Animals found in warm
habitats have long legs and large
ears.
Evolution and Genetics
• The incorporation of modern genetics into Darwin's
theory of evolution took place in the middle of the
20th century.
• This led to a focus on evolution as changes in the
allele frequencies of genes over time.
• Allele frequencies describe how common different
alleles for a gene are in the population.
Evolution and Genetics
• Mechanisms of Evolution
– Natural selection
• A specific allele may be advantageous and
allow organisms with the allele to reproduce
more than organisms with a different allele.
• More copies of the advantageous allele are
passed to the next generation, and the
frequency of the advantageous allele
increases in the population.
Evolution and Genetics
• Mechanisms of Evolution (continued)
– Mutation pressure
• A genetic mutation may be more likely to turn
one allele into a second allele than vice versa.
– Genetic drift
• Genetic drift is the evolution of populations due
to chance.
• Genetic drift is particularly important in small
populations.
Evolution and Genetics
• Mechanisms of Evolution (continued)
– Gene flow
• Changes in allele frequency result from the
movement of alleles into or out of a population,
such as through migration.
How Species Form
• A species is a group of organisms whose members
can breed with one another but not with members of
other species.
• Speciation is the formation of new species.
• The key to speciation is the evolution of
reproductive barriers that prevent two groups of
organisms from interbreeding.
How Species Form
• There are two kinds of reproductive barriers:
– Prezygotic reproductive barriers prevent
individuals of different species from mating or
prevent fertilization from occurring if they do
mate.
– Postzygotic reproductive barriers occur when
mating results in hybrids that do not survive or
are sterile, unable to reproduce.
How Species Form
• Two ways speciation can occur:
– In allopatric speciation, speciation occurs after a
geographic barrier divides a population into two
isolated populations.
How Species Form
• Two ways speciation can occur (continued):
– In sympatric speciation, speciation occurs without
a geographic barrier.
• Examples: hybridization and chromosomal
changes such as polyploidy
Evidence of Evolution
• Observations of natural selection in action
– Resistance to myxoma virus in Australian rabbits
– Peppered moth coloration and camouflage
– Antibiotic-resistant bacteria
– Evolution of the beaks of Darwin's finches after a
drought
– Many other documented examples
Evidence of Evolution
• Artificial selection
– In domesticated animals and crops, such as
dogs, racehorses, and corn
• Similarities in body structures
Evidence of Evolution
• Vestigial organs
• DNA and molecular evidence
– Similar DNA sequences in related species
• Patterns of development
Evidence of Evolution
• Hierarchical organization of living things
– Nested groups, or "groups within groups"
• Biogeography
– The study of how species are distributed on Earth
– Organisms evolved in a certain place and then
left descendants in the places where they were
able to spread.
Fossils: Earth's Tangible Evidence of
Evolution
• Fossils allow us to follow the evolution of certain
groups of organisms over time.
• The evolution of the whale blowhole
Fossils: Earth's Tangible Evidence of
Evolution
• The evolution and loss of whale hind legs
Fossils: Earth's Tangible Evidence of
Evolution
• Archaeopteryx, an early bird
The Evolution of Humans
• Humans are
– primates—we share an ancestry with monkeys
and apes.
– hominids—the primate group that includes Homo
sapiens and extinct relatives.
The Evolution of Humans
• The fossil record has allowed us to document some
aspects of human evolution.
History of Science: The Peppered Moth
History of Science: The Peppered Moth
• Peppered moths in England had always been light with a
scattering of peppery flakes. This made them well
camouflaged from birds (their main predators) in a
habitat of lichen-covered trees.
• During the Industrial Revolution, pollution caused trees
to become darkened with soot.
• More and more dark moths were seen in the peppered
moth population.
• After antipollution laws were passed, the soot
disappeared.
• Light moths increased in number. The dark moths have
all but disappeared.
History of Science: The Peppered Moth
• Kettlewell's experiments confirmed that natural selection
was responsible for changes in coloration in peppered
moth populations.
• Kettlewell released and recaptured marked moths. He
recaptured more dark moths in polluted habitats and
more light moths in unpolluted habitats.
• Kettlewell also placed moths on trees and filmed birds
eating the moths. Birds ate more light moths in polluted
habitats and more dark moths in unpolluted habitats.
• Challenges to Kettlewell's work resulted in his
experiments being repeated by Michael Majerus.
Kettlewell's results were confirmed.
Science and Society: Antibiotic-Resistant
Bacteria
• Antibiotic resistance has become a serious health issue.
• Antibiotic resistance is the result of natural selection.
• When a patient takes a course of antibiotics, a few
naturally resistant bacteria may survive the treatment.
These reproduce. Eventually, strains of bacteria exist
that cannot be controlled by the antibiotic.
• All antibiotic use contributes to antibiotic resistance.
• We must learn to take antibiotics only for bacterial
infections, and then to complete the course of treatment.
• Antibiotics should not be used to promote the growth of
livestock.
Science and Society: Antibiotic-Resistant
Bacteria
• Ways to slow the development of antibiotic
resistance in bacteria:
– Take antibiotics only when needed.
– Take the entire course of antibiotics.
– Use antibiotics responsibly in agriculture.

More Related Content

What's hot

Evolution
EvolutionEvolution
Evolution
Sukkur IBA
 
5.1 evidence for evolution
5.1 evidence for evolution5.1 evidence for evolution
5.1 evidence for evolution
Bob Smullen
 
Theories of evolution
Theories of evolutionTheories of evolution
Theories of evolution
Mera Luna Buenaflor
 
Modern synthetic theory of organic evolution shared by abdul qahar buneri
Modern synthetic theory of organic evolution shared by abdul qahar buneriModern synthetic theory of organic evolution shared by abdul qahar buneri
Modern synthetic theory of organic evolution shared by abdul qahar buneri
Abdul Qahar {{Abdul Wali Khan University Mardan}} (Buner Campus)
 
Origin and evolution of life
Origin and evolution of lifeOrigin and evolution of life
Origin and evolution of life
nasir shaikh
 
Origin of life
Origin of lifeOrigin of life
Origin of life
Lovnish Thakur
 
Biology - Chp 15 - Darwins Theory Of Evolution - PowerPoint
Biology - Chp 15 - Darwins Theory Of Evolution - PowerPointBiology - Chp 15 - Darwins Theory Of Evolution - PowerPoint
Biology - Chp 15 - Darwins Theory Of Evolution - PowerPoint
Mr. Walajtys
 
ZOO1 -Theories on the origin of life
ZOO1 -Theories on the origin of lifeZOO1 -Theories on the origin of life
ZOO1 -Theories on the origin of life
LeizlAnnaMaria
 
Patterns of Evolution
Patterns of EvolutionPatterns of Evolution
Patterns of Evolution
I Wonder Why Science
 
Ch15 lecture mechanisms of evolution
Ch15 lecture mechanisms of evolutionCh15 lecture mechanisms of evolution
Ch15 lecture mechanisms of evolution
Tia Hohler
 
Origin of life
Origin of lifeOrigin of life
Origin of life
Aftab Badshah
 
Darwinism.pptx
Darwinism.pptxDarwinism.pptx
Darwinism.pptx
GauriBholane1
 
Speciation
SpeciationSpeciation
Speciation
Geonyzl Alviola
 
Mass extinction
Mass extinctionMass extinction
Mass extinction
HARITHA ANIL KUMAR
 
B.sc.(micro) i em unit 1.2 origin of life
B.sc.(micro) i em unit 1.2 origin of lifeB.sc.(micro) i em unit 1.2 origin of life
B.sc.(micro) i em unit 1.2 origin of life
Rai University
 
Darwin’s theory of evolution
Darwin’s theory of evolutionDarwin’s theory of evolution
Darwin’s theory of evolution
Steve Johnson
 
Geological time Scale
Geological time  Scale Geological time  Scale
Geological time Scale
نوشی نایاب
 
Chapter 15.1 Darwin's Theory of Natural Selection
Chapter 15.1 Darwin's Theory of Natural SelectionChapter 15.1 Darwin's Theory of Natural Selection
Chapter 15.1 Darwin's Theory of Natural Selection
kathy_lambert
 
Evolution theories
Evolution theoriesEvolution theories
Evolution theories
Tauqeer Ahmad
 
02c types of natural selection
02c types of natural selection02c types of natural selection
02c types of natural selection
mrtangextrahelp
 

What's hot (20)

Evolution
EvolutionEvolution
Evolution
 
5.1 evidence for evolution
5.1 evidence for evolution5.1 evidence for evolution
5.1 evidence for evolution
 
Theories of evolution
Theories of evolutionTheories of evolution
Theories of evolution
 
Modern synthetic theory of organic evolution shared by abdul qahar buneri
Modern synthetic theory of organic evolution shared by abdul qahar buneriModern synthetic theory of organic evolution shared by abdul qahar buneri
Modern synthetic theory of organic evolution shared by abdul qahar buneri
 
Origin and evolution of life
Origin and evolution of lifeOrigin and evolution of life
Origin and evolution of life
 
Origin of life
Origin of lifeOrigin of life
Origin of life
 
Biology - Chp 15 - Darwins Theory Of Evolution - PowerPoint
Biology - Chp 15 - Darwins Theory Of Evolution - PowerPointBiology - Chp 15 - Darwins Theory Of Evolution - PowerPoint
Biology - Chp 15 - Darwins Theory Of Evolution - PowerPoint
 
ZOO1 -Theories on the origin of life
ZOO1 -Theories on the origin of lifeZOO1 -Theories on the origin of life
ZOO1 -Theories on the origin of life
 
Patterns of Evolution
Patterns of EvolutionPatterns of Evolution
Patterns of Evolution
 
Ch15 lecture mechanisms of evolution
Ch15 lecture mechanisms of evolutionCh15 lecture mechanisms of evolution
Ch15 lecture mechanisms of evolution
 
Origin of life
Origin of lifeOrigin of life
Origin of life
 
Darwinism.pptx
Darwinism.pptxDarwinism.pptx
Darwinism.pptx
 
Speciation
SpeciationSpeciation
Speciation
 
Mass extinction
Mass extinctionMass extinction
Mass extinction
 
B.sc.(micro) i em unit 1.2 origin of life
B.sc.(micro) i em unit 1.2 origin of lifeB.sc.(micro) i em unit 1.2 origin of life
B.sc.(micro) i em unit 1.2 origin of life
 
Darwin’s theory of evolution
Darwin’s theory of evolutionDarwin’s theory of evolution
Darwin’s theory of evolution
 
Geological time Scale
Geological time  Scale Geological time  Scale
Geological time Scale
 
Chapter 15.1 Darwin's Theory of Natural Selection
Chapter 15.1 Darwin's Theory of Natural SelectionChapter 15.1 Darwin's Theory of Natural Selection
Chapter 15.1 Darwin's Theory of Natural Selection
 
Evolution theories
Evolution theoriesEvolution theories
Evolution theories
 
02c types of natural selection
02c types of natural selection02c types of natural selection
02c types of natural selection
 

Viewers also liked

Origin of life
Origin of lifeOrigin of life
Origin of life
damarisb
 
The origin and evolution of life on earth
The origin and evolution of life on earthThe origin and evolution of life on earth
The origin and evolution of life on earth
Emmanuel Aguon
 
Chlorine uses & safety
Chlorine uses & safetyChlorine uses & safety
Chlorine uses & safety
umar farooq
 
Understanding Evolution - Life goes on
Understanding Evolution - Life goes onUnderstanding Evolution - Life goes on
Understanding Evolution - Life goes on
Harshal Hayatnagarkar
 
Unit4: Cells
Unit4: CellsUnit4: Cells
Unit4: Cells
aurorabiologia
 
The Cell Cycle and Division
The Cell Cycle and DivisionThe Cell Cycle and Division
The Cell Cycle and Division
Melinda MacDonald
 
Chapter 16 & 17 Evolution of Populations and The History of Life
Chapter 16 & 17 Evolution of Populations and The History of LifeChapter 16 & 17 Evolution of Populations and The History of Life
Chapter 16 & 17 Evolution of Populations and The History of Life
stockyard71
 
Chlorine
ChlorineChlorine
Chlorine
guest635b2f
 
Vård i livets slutskede
Vård i livets slutskedeVård i livets slutskede
Vård i livets slutskede
Frfia
 
Evolution
EvolutionEvolution
Evolution
Sandåkerskolan
 
Sammanfattning arv och evolution
Sammanfattning arv och evolutionSammanfattning arv och evolution
Sammanfattning arv och evolution
davidloving
 
Lena Koinberg | FBK Kemi: Rena ämnen och blandningar
Lena Koinberg | FBK Kemi: Rena ämnen och blandningarLena Koinberg | FBK Kemi: Rena ämnen och blandningar
Lena Koinberg | FBK Kemi: Rena ämnen och blandningar
Lena Koinberg
 
Kärnkraft
KärnkraftKärnkraft
Kärnkraft
nisse100
 
FBK SVA - Kalender
FBK SVA - KalenderFBK SVA - Kalender
FBK SVA - Kalender
Lena Koinberg
 
Lena Koinberg | FBK Fysik: Värme
Lena Koinberg | FBK Fysik: VärmeLena Koinberg | FBK Fysik: Värme
Lena Koinberg | FBK Fysik: Värme
Lena Koinberg
 
Lena Koinberg | FBK Fysik: Magnetism
Lena Koinberg | FBK Fysik: MagnetismLena Koinberg | FBK Fysik: Magnetism
Lena Koinberg | FBK Fysik: Magnetism
Lena Koinberg
 
Lena Koinberg | FBK Fysik: Massa och Tyngdkraft
Lena Koinberg | FBK Fysik: Massa och TyngdkraftLena Koinberg | FBK Fysik: Massa och Tyngdkraft
Lena Koinberg | FBK Fysik: Massa och Tyngdkraft
Lena Koinberg
 
Lena Koinberg | FBK Fysik: Solsystemet
Lena Koinberg | FBK Fysik: SolsystemetLena Koinberg | FBK Fysik: Solsystemet
Lena Koinberg | FBK Fysik: Solsystemet
Lena Koinberg
 

Viewers also liked (20)

Origin of life
Origin of lifeOrigin of life
Origin of life
 
The origin and evolution of life on earth
The origin and evolution of life on earthThe origin and evolution of life on earth
The origin and evolution of life on earth
 
Chlorine uses & safety
Chlorine uses & safetyChlorine uses & safety
Chlorine uses & safety
 
Understanding Evolution - Life goes on
Understanding Evolution - Life goes onUnderstanding Evolution - Life goes on
Understanding Evolution - Life goes on
 
Unit4: Cells
Unit4: CellsUnit4: Cells
Unit4: Cells
 
The Cell Cycle and Division
The Cell Cycle and DivisionThe Cell Cycle and Division
The Cell Cycle and Division
 
Chapter 16 & 17 Evolution of Populations and The History of Life
Chapter 16 & 17 Evolution of Populations and The History of LifeChapter 16 & 17 Evolution of Populations and The History of Life
Chapter 16 & 17 Evolution of Populations and The History of Life
 
Chlorine
ChlorineChlorine
Chlorine
 
Bi evolution
Bi   evolutionBi   evolution
Bi evolution
 
R&r åk9
R&r åk9R&r åk9
R&r åk9
 
Vård i livets slutskede
Vård i livets slutskedeVård i livets slutskede
Vård i livets slutskede
 
Evolution
EvolutionEvolution
Evolution
 
Sammanfattning arv och evolution
Sammanfattning arv och evolutionSammanfattning arv och evolution
Sammanfattning arv och evolution
 
Lena Koinberg | FBK Kemi: Rena ämnen och blandningar
Lena Koinberg | FBK Kemi: Rena ämnen och blandningarLena Koinberg | FBK Kemi: Rena ämnen och blandningar
Lena Koinberg | FBK Kemi: Rena ämnen och blandningar
 
Kärnkraft
KärnkraftKärnkraft
Kärnkraft
 
FBK SVA - Kalender
FBK SVA - KalenderFBK SVA - Kalender
FBK SVA - Kalender
 
Lena Koinberg | FBK Fysik: Värme
Lena Koinberg | FBK Fysik: VärmeLena Koinberg | FBK Fysik: Värme
Lena Koinberg | FBK Fysik: Värme
 
Lena Koinberg | FBK Fysik: Magnetism
Lena Koinberg | FBK Fysik: MagnetismLena Koinberg | FBK Fysik: Magnetism
Lena Koinberg | FBK Fysik: Magnetism
 
Lena Koinberg | FBK Fysik: Massa och Tyngdkraft
Lena Koinberg | FBK Fysik: Massa och TyngdkraftLena Koinberg | FBK Fysik: Massa och Tyngdkraft
Lena Koinberg | FBK Fysik: Massa och Tyngdkraft
 
Lena Koinberg | FBK Fysik: Solsystemet
Lena Koinberg | FBK Fysik: SolsystemetLena Koinberg | FBK Fysik: Solsystemet
Lena Koinberg | FBK Fysik: Solsystemet
 

Similar to Ch17 evolution of life

Evolution slideshare
Evolution slideshare Evolution slideshare
Evolution slideshare
anika55
 
Evolution by mohan bio
Evolution by mohan bioEvolution by mohan bio
Evolution by mohan bio
mohan bio
 
Science 10 quarter 3.... Biodiversity.ppt
Science 10 quarter 3.... Biodiversity.pptScience 10 quarter 3.... Biodiversity.ppt
Science 10 quarter 3.... Biodiversity.ppt
MichelleAglipay
 
Chapter15 evolution(darwin)
Chapter15 evolution(darwin)Chapter15 evolution(darwin)
Chapter15 evolution(darwin)
katiecam21
 
EVOLUTION Class XII Biology based on NCERT text book .pptx
EVOLUTION Class XII Biology based on NCERT text book .pptxEVOLUTION Class XII Biology based on NCERT text book .pptx
EVOLUTION Class XII Biology based on NCERT text book .pptx
DrUpadhyay
 
2 Biological Change.ppt
2 Biological Change.ppt2 Biological Change.ppt
2 Biological Change.ppt
KimberlyAnnePagdanga1
 
Evolution part 2
Evolution part 2Evolution part 2
Evolution part 2
Maria Donohue
 
Xii chap 7
Xii chap 7Xii chap 7
Xii chap 7
RashmiSinha61
 
12 biology notes_ch07_evolution
12 biology notes_ch07_evolution12 biology notes_ch07_evolution
12 biology notes_ch07_evolution
Mayank Sharma
 
Evolution
EvolutionEvolution
Evolution
clear_rivers
 
Biology - Chp 15 - Darwins Theory Of Evolution - PowerPoint
Biology - Chp 15 - Darwins Theory Of Evolution - PowerPointBiology - Chp 15 - Darwins Theory Of Evolution - PowerPoint
Biology - Chp 15 - Darwins Theory Of Evolution - PowerPoint
Mel Anthony Pepito
 
Evolution
EvolutionEvolution
Evolution
Genevia Vincent
 
evolution-161023055712.pptx GENERAL BIOLOGY
evolution-161023055712.pptx GENERAL BIOLOGYevolution-161023055712.pptx GENERAL BIOLOGY
evolution-161023055712.pptx GENERAL BIOLOGY
IneleElliaAgRe
 
evolution-161023055712 (1) geology .pptx
evolution-161023055712 (1) geology .pptxevolution-161023055712 (1) geology .pptx
evolution-161023055712 (1) geology .pptx
MAHAZELTEOLOGO3
 
Evolution and human evolution
Evolution and human evolutionEvolution and human evolution
Evolution and human evolution
Kunal Datiwal
 
Evolution Presentation
Evolution PresentationEvolution Presentation
Evolution Presentation
Reginald V. Finley Sr. M.Ed.
 
HISTORY OF EVOLUTION
HISTORY OF EVOLUTION HISTORY OF EVOLUTION
HISTORY OF EVOLUTION
SalmanShaikh633286
 
Evolution powerpoint!
Evolution powerpoint!Evolution powerpoint!
Evolution powerpoint!
Mneel1
 
The-TIES-Middle-School-Evolution-Presentation-1-1.pptx
The-TIES-Middle-School-Evolution-Presentation-1-1.pptxThe-TIES-Middle-School-Evolution-Presentation-1-1.pptx
The-TIES-Middle-School-Evolution-Presentation-1-1.pptx
TonyStark449263
 
Sealey evolution
Sealey evolutionSealey evolution
Sealey evolution
ssealey
 

Similar to Ch17 evolution of life (20)

Evolution slideshare
Evolution slideshare Evolution slideshare
Evolution slideshare
 
Evolution by mohan bio
Evolution by mohan bioEvolution by mohan bio
Evolution by mohan bio
 
Science 10 quarter 3.... Biodiversity.ppt
Science 10 quarter 3.... Biodiversity.pptScience 10 quarter 3.... Biodiversity.ppt
Science 10 quarter 3.... Biodiversity.ppt
 
Chapter15 evolution(darwin)
Chapter15 evolution(darwin)Chapter15 evolution(darwin)
Chapter15 evolution(darwin)
 
EVOLUTION Class XII Biology based on NCERT text book .pptx
EVOLUTION Class XII Biology based on NCERT text book .pptxEVOLUTION Class XII Biology based on NCERT text book .pptx
EVOLUTION Class XII Biology based on NCERT text book .pptx
 
2 Biological Change.ppt
2 Biological Change.ppt2 Biological Change.ppt
2 Biological Change.ppt
 
Evolution part 2
Evolution part 2Evolution part 2
Evolution part 2
 
Xii chap 7
Xii chap 7Xii chap 7
Xii chap 7
 
12 biology notes_ch07_evolution
12 biology notes_ch07_evolution12 biology notes_ch07_evolution
12 biology notes_ch07_evolution
 
Evolution
EvolutionEvolution
Evolution
 
Biology - Chp 15 - Darwins Theory Of Evolution - PowerPoint
Biology - Chp 15 - Darwins Theory Of Evolution - PowerPointBiology - Chp 15 - Darwins Theory Of Evolution - PowerPoint
Biology - Chp 15 - Darwins Theory Of Evolution - PowerPoint
 
Evolution
EvolutionEvolution
Evolution
 
evolution-161023055712.pptx GENERAL BIOLOGY
evolution-161023055712.pptx GENERAL BIOLOGYevolution-161023055712.pptx GENERAL BIOLOGY
evolution-161023055712.pptx GENERAL BIOLOGY
 
evolution-161023055712 (1) geology .pptx
evolution-161023055712 (1) geology .pptxevolution-161023055712 (1) geology .pptx
evolution-161023055712 (1) geology .pptx
 
Evolution and human evolution
Evolution and human evolutionEvolution and human evolution
Evolution and human evolution
 
Evolution Presentation
Evolution PresentationEvolution Presentation
Evolution Presentation
 
HISTORY OF EVOLUTION
HISTORY OF EVOLUTION HISTORY OF EVOLUTION
HISTORY OF EVOLUTION
 
Evolution powerpoint!
Evolution powerpoint!Evolution powerpoint!
Evolution powerpoint!
 
The-TIES-Middle-School-Evolution-Presentation-1-1.pptx
The-TIES-Middle-School-Evolution-Presentation-1-1.pptxThe-TIES-Middle-School-Evolution-Presentation-1-1.pptx
The-TIES-Middle-School-Evolution-Presentation-1-1.pptx
 
Sealey evolution
Sealey evolutionSealey evolution
Sealey evolution
 

More from coolscienceguy

Ch18 animal diversity
Ch18 animal diversityCh18 animal diversity
Ch18 animal diversity
coolscienceguy
 
Ch16 genetics
Ch16  geneticsCh16  genetics
Ch16 genetics
coolscienceguy
 
Ch15 l the basic unit of life
Ch15 l the basic unit of lifeCh15 l the basic unit of life
Ch15 l the basic unit of life
coolscienceguy
 
Chapter 14 organic compounds
Chapter 14 organic compoundsChapter 14 organic compounds
Chapter 14 organic compounds
coolscienceguy
 
Chapter 13 chemical reactions
Chapter 13 chemical reactionsChapter 13 chemical reactions
Chapter 13 chemical reactions
coolscienceguy
 
Chapter 12 chemical bonds and mixtures
Chapter 12 chemical bonds and mixturesChapter 12 chemical bonds and mixtures
Chapter 12 chemical bonds and mixtures
coolscienceguy
 
Vaccines herd immunity anti vaccine movt
Vaccines herd immunity anti vaccine movtVaccines herd immunity anti vaccine movt
Vaccines herd immunity anti vaccine movt
coolscienceguy
 
Ch11 lecture outline
Ch11 lecture outlineCh11 lecture outline
Ch11 lecture outline
coolscienceguy
 
Chapter 9 atoms and the periodic table
Chapter 9 atoms and the periodic tableChapter 9 atoms and the periodic table
Chapter 9 atoms and the periodic table
coolscienceguy
 
Chapter 1 lecture about sciecnce
Chapter 1 lecture about sciecnceChapter 1 lecture about sciecnce
Chapter 1 lecture about sciecnce
coolscienceguy
 

More from coolscienceguy (10)

Ch18 animal diversity
Ch18 animal diversityCh18 animal diversity
Ch18 animal diversity
 
Ch16 genetics
Ch16  geneticsCh16  genetics
Ch16 genetics
 
Ch15 l the basic unit of life
Ch15 l the basic unit of lifeCh15 l the basic unit of life
Ch15 l the basic unit of life
 
Chapter 14 organic compounds
Chapter 14 organic compoundsChapter 14 organic compounds
Chapter 14 organic compounds
 
Chapter 13 chemical reactions
Chapter 13 chemical reactionsChapter 13 chemical reactions
Chapter 13 chemical reactions
 
Chapter 12 chemical bonds and mixtures
Chapter 12 chemical bonds and mixturesChapter 12 chemical bonds and mixtures
Chapter 12 chemical bonds and mixtures
 
Vaccines herd immunity anti vaccine movt
Vaccines herd immunity anti vaccine movtVaccines herd immunity anti vaccine movt
Vaccines herd immunity anti vaccine movt
 
Ch11 lecture outline
Ch11 lecture outlineCh11 lecture outline
Ch11 lecture outline
 
Chapter 9 atoms and the periodic table
Chapter 9 atoms and the periodic tableChapter 9 atoms and the periodic table
Chapter 9 atoms and the periodic table
 
Chapter 1 lecture about sciecnce
Chapter 1 lecture about sciecnceChapter 1 lecture about sciecnce
Chapter 1 lecture about sciecnce
 

Recently uploaded

A NICER VIEW OF THE NEAREST AND BRIGHTEST MILLISECOND PULSAR: PSR J0437−4715
A NICER VIEW OF THE NEAREST AND BRIGHTEST MILLISECOND PULSAR: PSR J0437−4715A NICER VIEW OF THE NEAREST AND BRIGHTEST MILLISECOND PULSAR: PSR J0437−4715
A NICER VIEW OF THE NEAREST AND BRIGHTEST MILLISECOND PULSAR: PSR J0437−4715
Sérgio Sacani
 
Fish in the Loop: Exploring RAS - Julie Hansen Bergstedt
Fish in the Loop: Exploring RAS - Julie Hansen BergstedtFish in the Loop: Exploring RAS - Julie Hansen Bergstedt
Fish in the Loop: Exploring RAS - Julie Hansen Bergstedt
Faculty of Applied Chemistry and Materials Science
 
ellipticytescausesprognosistreatment-240622051139-23d50b05.pptx
ellipticytescausesprognosistreatment-240622051139-23d50b05.pptxellipticytescausesprognosistreatment-240622051139-23d50b05.pptx
ellipticytescausesprognosistreatment-240622051139-23d50b05.pptx
muralinath2
 
Synopsis: Analysis of a Metallic Specimen
Synopsis: Analysis of a Metallic SpecimenSynopsis: Analysis of a Metallic Specimen
Synopsis: Analysis of a Metallic Specimen
Sérgio Sacani
 
How Does Simulation-Based Testing for Self-Driving Cars Match Human Perception?
How Does Simulation-Based Testing for Self-Driving Cars Match Human Perception?How Does Simulation-Based Testing for Self-Driving Cars Match Human Perception?
How Does Simulation-Based Testing for Self-Driving Cars Match Human Perception?
Christian Birchler
 
Types of Hypersensitivity Reactions.pptx
Types of Hypersensitivity Reactions.pptxTypes of Hypersensitivity Reactions.pptx
Types of Hypersensitivity Reactions.pptx
Isha Pandey
 
Celebrity Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl S...
Celebrity Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl S...Celebrity Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl S...
Celebrity Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl S...
bellared2
 
Composting blue materials - Joshua Cabell
Composting blue materials - Joshua CabellComposting blue materials - Joshua Cabell
Composting blue materials - Joshua Cabell
Faculty of Applied Chemistry and Materials Science
 
Simulations of pulsed overpressure jets: formation of bellows and ripples in ...
Simulations of pulsed overpressure jets: formation of bellows and ripples in ...Simulations of pulsed overpressure jets: formation of bellows and ripples in ...
Simulations of pulsed overpressure jets: formation of bellows and ripples in ...
Sérgio Sacani
 
A hot-Jupiter progenitor on a super-eccentric retrograde orbit
A hot-Jupiter progenitor on a super-eccentric retrograde orbitA hot-Jupiter progenitor on a super-eccentric retrograde orbit
A hot-Jupiter progenitor on a super-eccentric retrograde orbit
Sérgio Sacani
 
No black holes from light einstein general relativity
No black holes from light einstein general relativityNo black holes from light einstein general relativity
No black holes from light einstein general relativity
Sérgio Sacani
 
Burn child health Nursing 3rd year presentation..pptx
Burn child health Nursing 3rd year presentation..pptxBurn child health Nursing 3rd year presentation..pptx
Burn child health Nursing 3rd year presentation..pptx
sohil4260
 
End of pipe treatment: Unlocking the potential of RAS waste - Carlos Octavio ...
End of pipe treatment: Unlocking the potential of RAS waste - Carlos Octavio ...End of pipe treatment: Unlocking the potential of RAS waste - Carlos Octavio ...
End of pipe treatment: Unlocking the potential of RAS waste - Carlos Octavio ...
Faculty of Applied Chemistry and Materials Science
 
Phytoremediation: Harnessing Nature's Power with Phytoremediation
Phytoremediation: Harnessing Nature's Power with PhytoremediationPhytoremediation: Harnessing Nature's Power with Phytoremediation
Phytoremediation: Harnessing Nature's Power with Phytoremediation
Gurjant Singh
 
Analytical methods for blue residues characterization - Oana Crina Bujor
Analytical methods for blue residues characterization - Oana Crina BujorAnalytical methods for blue residues characterization - Oana Crina Bujor
Analytical methods for blue residues characterization - Oana Crina Bujor
Faculty of Applied Chemistry and Materials Science
 
Post RN - Biochemistry (Unit 1) Basic concept of Chemistry
Post RN - Biochemistry (Unit 1) Basic concept of ChemistryPost RN - Biochemistry (Unit 1) Basic concept of Chemistry
Post RN - Biochemistry (Unit 1) Basic concept of Chemistry
Areesha Ahmad
 
Rice Genome Project a complete saga .(1).pptx
Rice Genome  Project a complete saga .(1).pptxRice Genome  Project a complete saga .(1).pptx
Rice Genome Project a complete saga .(1).pptx
SoumyaDixit11
 
Potential of Marine Renewable and Non renewable energy.pptx
Potential of Marine Renewable and Non renewable energy.pptxPotential of Marine Renewable and Non renewable energy.pptx
Potential of Marine Renewable and Non renewable energy.pptx
J. Bovas Joel BFSc
 
Traditional, current and future use of fish and seaweed for fertilisation - ...
Traditional, current and future use of fish and seaweed for fertilisation -  ...Traditional, current and future use of fish and seaweed for fertilisation -  ...
Traditional, current and future use of fish and seaweed for fertilisation - ...
Faculty of Applied Chemistry and Materials Science
 
The CGIAR needs a revolution John McIntire a, Achim Dobermann b
The CGIAR needs a revolution John McIntire a, Achim Dobermann bThe CGIAR needs a revolution John McIntire a, Achim Dobermann b
The CGIAR needs a revolution John McIntire a, Achim Dobermann b
Abdellah HAMMA
 

Recently uploaded (20)

A NICER VIEW OF THE NEAREST AND BRIGHTEST MILLISECOND PULSAR: PSR J0437−4715
A NICER VIEW OF THE NEAREST AND BRIGHTEST MILLISECOND PULSAR: PSR J0437−4715A NICER VIEW OF THE NEAREST AND BRIGHTEST MILLISECOND PULSAR: PSR J0437−4715
A NICER VIEW OF THE NEAREST AND BRIGHTEST MILLISECOND PULSAR: PSR J0437−4715
 
Fish in the Loop: Exploring RAS - Julie Hansen Bergstedt
Fish in the Loop: Exploring RAS - Julie Hansen BergstedtFish in the Loop: Exploring RAS - Julie Hansen Bergstedt
Fish in the Loop: Exploring RAS - Julie Hansen Bergstedt
 
ellipticytescausesprognosistreatment-240622051139-23d50b05.pptx
ellipticytescausesprognosistreatment-240622051139-23d50b05.pptxellipticytescausesprognosistreatment-240622051139-23d50b05.pptx
ellipticytescausesprognosistreatment-240622051139-23d50b05.pptx
 
Synopsis: Analysis of a Metallic Specimen
Synopsis: Analysis of a Metallic SpecimenSynopsis: Analysis of a Metallic Specimen
Synopsis: Analysis of a Metallic Specimen
 
How Does Simulation-Based Testing for Self-Driving Cars Match Human Perception?
How Does Simulation-Based Testing for Self-Driving Cars Match Human Perception?How Does Simulation-Based Testing for Self-Driving Cars Match Human Perception?
How Does Simulation-Based Testing for Self-Driving Cars Match Human Perception?
 
Types of Hypersensitivity Reactions.pptx
Types of Hypersensitivity Reactions.pptxTypes of Hypersensitivity Reactions.pptx
Types of Hypersensitivity Reactions.pptx
 
Celebrity Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl S...
Celebrity Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl S...Celebrity Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl S...
Celebrity Girls Call Navi Mumbai 🎈🔥9920725232 🔥💋🎈 Provide Best And Top Girl S...
 
Composting blue materials - Joshua Cabell
Composting blue materials - Joshua CabellComposting blue materials - Joshua Cabell
Composting blue materials - Joshua Cabell
 
Simulations of pulsed overpressure jets: formation of bellows and ripples in ...
Simulations of pulsed overpressure jets: formation of bellows and ripples in ...Simulations of pulsed overpressure jets: formation of bellows and ripples in ...
Simulations of pulsed overpressure jets: formation of bellows and ripples in ...
 
A hot-Jupiter progenitor on a super-eccentric retrograde orbit
A hot-Jupiter progenitor on a super-eccentric retrograde orbitA hot-Jupiter progenitor on a super-eccentric retrograde orbit
A hot-Jupiter progenitor on a super-eccentric retrograde orbit
 
No black holes from light einstein general relativity
No black holes from light einstein general relativityNo black holes from light einstein general relativity
No black holes from light einstein general relativity
 
Burn child health Nursing 3rd year presentation..pptx
Burn child health Nursing 3rd year presentation..pptxBurn child health Nursing 3rd year presentation..pptx
Burn child health Nursing 3rd year presentation..pptx
 
End of pipe treatment: Unlocking the potential of RAS waste - Carlos Octavio ...
End of pipe treatment: Unlocking the potential of RAS waste - Carlos Octavio ...End of pipe treatment: Unlocking the potential of RAS waste - Carlos Octavio ...
End of pipe treatment: Unlocking the potential of RAS waste - Carlos Octavio ...
 
Phytoremediation: Harnessing Nature's Power with Phytoremediation
Phytoremediation: Harnessing Nature's Power with PhytoremediationPhytoremediation: Harnessing Nature's Power with Phytoremediation
Phytoremediation: Harnessing Nature's Power with Phytoremediation
 
Analytical methods for blue residues characterization - Oana Crina Bujor
Analytical methods for blue residues characterization - Oana Crina BujorAnalytical methods for blue residues characterization - Oana Crina Bujor
Analytical methods for blue residues characterization - Oana Crina Bujor
 
Post RN - Biochemistry (Unit 1) Basic concept of Chemistry
Post RN - Biochemistry (Unit 1) Basic concept of ChemistryPost RN - Biochemistry (Unit 1) Basic concept of Chemistry
Post RN - Biochemistry (Unit 1) Basic concept of Chemistry
 
Rice Genome Project a complete saga .(1).pptx
Rice Genome  Project a complete saga .(1).pptxRice Genome  Project a complete saga .(1).pptx
Rice Genome Project a complete saga .(1).pptx
 
Potential of Marine Renewable and Non renewable energy.pptx
Potential of Marine Renewable and Non renewable energy.pptxPotential of Marine Renewable and Non renewable energy.pptx
Potential of Marine Renewable and Non renewable energy.pptx
 
Traditional, current and future use of fish and seaweed for fertilisation - ...
Traditional, current and future use of fish and seaweed for fertilisation -  ...Traditional, current and future use of fish and seaweed for fertilisation -  ...
Traditional, current and future use of fish and seaweed for fertilisation - ...
 
The CGIAR needs a revolution John McIntire a, Achim Dobermann b
The CGIAR needs a revolution John McIntire a, Achim Dobermann bThe CGIAR needs a revolution John McIntire a, Achim Dobermann b
The CGIAR needs a revolution John McIntire a, Achim Dobermann b
 

Ch17 evolution of life

  • 1. Chapter 17: The Evolution of Life Principles of Science II
  • 2. This lecture will help you understand: • The Origin of Life • Did Life on Earth Originate on Mars? • Early Life on Earth • Charles Darwin and The Origin of Species • How Natural Selection Works • Adaptation • Staying Warm and Keeping Cool • Evolution and Genetics • How Species Form • Evidence of Evolution • Fossils: Earth's Tangible Evidence of Evolution • The Evolution of Humans • History of Science: The Peppered Moth • Science and Society: Antibiotic-Resistant Bacteria
  • 3. The Origin of Life • For thousands of years, people believed that life was created through spontaneous generation, the sudden emergence of living organisms from nonliving materials.
  • 4. The Origin of Life • Louis Pasteur demonstrated that life did not arise from nonlife.
  • 5. The Origin of Life • Life originated billions of years ago on a young Earth very different from the Earth of today. • The Miller and Urey experiment modeled the young Earth's atmosphere and oceans. • When Miller and Urey shot electric sparks through the model to simulate lightning, complex organic molecules formed.
  • 6. The Origin of Life • There are two alternative hypotheses for the origin of organic molecules on Earth: – Organic molecules came to Earth on incoming meteorites. – Organic molecules were synthesized in deep- sea environments. • But, how do you get from organic molecules to cells?
  • 7. The Origin of Life • Liposomes form spontaneously when certain lipids are added to water. Liposomes – have double membranes similar to cell membranes. – can grow, shrink, and divide. – run chemical reactions inside their membranes. – control what molecules move into and out of them.
  • 8. The Origin of Life • Living cells also need genes. • Scientists now believe that the first genes were made of RNA, not DNA. – Short strands of RNA can spontaneously assemble from individual RNA nucleotides. – RNA can replicate by itself. • Liposomes may have captured RNA "genes," forming the first primitive cells on Earth.
  • 9. Did Life on Earth Originate on Mars? • In 1996, scientists found what resembled tiny, fossilized bacteria in a Martian meteorite. • Mars was once a much warmer and wetter planet. • The supposed fossils may be too small to be fossilized bacteria. • NASA continues to explore the possibility of life on Mars.
  • 10. Early Life on Earth • The origin of autotrophs – Earth's earliest living organisms • were marine prokaryotes. • lived with no free oxygen. • were heterotrophs that obtained energy and food from outside sources. – The evolution of autotrophs, organisms able to convert inorganic molecules into food and organic molecules, was a key event in the history of life. • Photosynthesizers use energy from the Sun. • Chemoautotrophs use energy from certain inorganic chemicals.
  • 11. Early Life on Earth • The oxygenation of the atmosphere – Cyanobacteria are photosynthetic bacteria that produce oxygen as a by-product of photosynthesis.
  • 12. Early Life on Earth • The first eukaryotes – Eukaryotes appeared about 2 billion years ago. – The nucleus and most organelles most likely originated from inward foldings of the cell membrane. – According to the endosymbiotic theory, mitochondria and chloroplasts evolved from prokaryotes living inside the earliest eukaryotic cells.
  • 13. Charles Darwin and The Origin of Species • For thousands of years, people believed that species on Earth did not change. • But then what are fossils?
  • 14. Charles Darwin and The Origin of Species • Jean Baptiste Lamarck argued that modern species were descended from ancestors that had evolved to become better adapted to their environments. • Lamarck believed that organisms acquired new traits over their lifetimes and then passed these traits to their offspring. He called this the inheritance of acquired characteristics.
  • 15. Charles Darwin and The Origin of Species • Charles Darwin argued that evolution—inherited changes in populations of organisms over time— had produced all the living forms on Earth.
  • 16. Charles Darwin and The Origin of Species • Darwin was inspired by the observations he made as the naturalist aboard the H.M.S. Beagle as it sailed around South America from 1831 to 1836. • For example, the 13 species of finches on the Galápagos Islands varied in beak size and shape, depending on their diet. How had the beaks of the finches come to vary in this way?
  • 17. Charles Darwin and The Origin of Species • Darwin was also inspired by – the work of geologist Charles Lyell, who argued that Earth's geologic features were built by gradual processes over millennia. – the work of economist Thomas Malthus, who wrote about famine and the struggle of humans over resources.
  • 18. How Natural Selection Works • In any population of organisms, individuals have many traits that show variation. • Traits that are determined at least partly by genes are heritable, passed from parents to offspring. • Organisms that possess variable heritable traits that are advantageous leave more offspring than organisms without the advantageous traits. This is natural selection. • Advantageous traits become more common in a population, resulting in adaptation.
  • 20. Adaptation • Adaptations are traits that make organisms well suited to living and reproducing in their environments. • Adaptations can relate to various aspects of an organism's life: – Survival adaptations – Sexual selection, which leads to the evolution of adaptations that help organisms acquire mates – Bearing and raising young
  • 21. Staying Warm and Keeping Cool • Mammals thermoregulate, maintaining a fairly constant body temperature. • The surface-area-to-volume ratio is an important factor in thermoregulation. It affects the size and shape of animals. – Size: Animals found in cold habitats are often larger than related species living in warm habitats. – Shape: Animals found in cold habitats tend to have short legs and small ears. Animals found in warm habitats have long legs and large ears.
  • 22. Evolution and Genetics • The incorporation of modern genetics into Darwin's theory of evolution took place in the middle of the 20th century. • This led to a focus on evolution as changes in the allele frequencies of genes over time. • Allele frequencies describe how common different alleles for a gene are in the population.
  • 23. Evolution and Genetics • Mechanisms of Evolution – Natural selection • A specific allele may be advantageous and allow organisms with the allele to reproduce more than organisms with a different allele. • More copies of the advantageous allele are passed to the next generation, and the frequency of the advantageous allele increases in the population.
  • 24. Evolution and Genetics • Mechanisms of Evolution (continued) – Mutation pressure • A genetic mutation may be more likely to turn one allele into a second allele than vice versa. – Genetic drift • Genetic drift is the evolution of populations due to chance. • Genetic drift is particularly important in small populations.
  • 25. Evolution and Genetics • Mechanisms of Evolution (continued) – Gene flow • Changes in allele frequency result from the movement of alleles into or out of a population, such as through migration.
  • 26. How Species Form • A species is a group of organisms whose members can breed with one another but not with members of other species. • Speciation is the formation of new species. • The key to speciation is the evolution of reproductive barriers that prevent two groups of organisms from interbreeding.
  • 27. How Species Form • There are two kinds of reproductive barriers: – Prezygotic reproductive barriers prevent individuals of different species from mating or prevent fertilization from occurring if they do mate. – Postzygotic reproductive barriers occur when mating results in hybrids that do not survive or are sterile, unable to reproduce.
  • 28. How Species Form • Two ways speciation can occur: – In allopatric speciation, speciation occurs after a geographic barrier divides a population into two isolated populations.
  • 29. How Species Form • Two ways speciation can occur (continued): – In sympatric speciation, speciation occurs without a geographic barrier. • Examples: hybridization and chromosomal changes such as polyploidy
  • 30. Evidence of Evolution • Observations of natural selection in action – Resistance to myxoma virus in Australian rabbits – Peppered moth coloration and camouflage – Antibiotic-resistant bacteria – Evolution of the beaks of Darwin's finches after a drought – Many other documented examples
  • 31. Evidence of Evolution • Artificial selection – In domesticated animals and crops, such as dogs, racehorses, and corn • Similarities in body structures
  • 32. Evidence of Evolution • Vestigial organs • DNA and molecular evidence – Similar DNA sequences in related species • Patterns of development
  • 33. Evidence of Evolution • Hierarchical organization of living things – Nested groups, or "groups within groups" • Biogeography – The study of how species are distributed on Earth – Organisms evolved in a certain place and then left descendants in the places where they were able to spread.
  • 34. Fossils: Earth's Tangible Evidence of Evolution • Fossils allow us to follow the evolution of certain groups of organisms over time. • The evolution of the whale blowhole
  • 35. Fossils: Earth's Tangible Evidence of Evolution • The evolution and loss of whale hind legs
  • 36. Fossils: Earth's Tangible Evidence of Evolution • Archaeopteryx, an early bird
  • 37. The Evolution of Humans • Humans are – primates—we share an ancestry with monkeys and apes. – hominids—the primate group that includes Homo sapiens and extinct relatives.
  • 38. The Evolution of Humans • The fossil record has allowed us to document some aspects of human evolution.
  • 39. History of Science: The Peppered Moth
  • 40. History of Science: The Peppered Moth • Peppered moths in England had always been light with a scattering of peppery flakes. This made them well camouflaged from birds (their main predators) in a habitat of lichen-covered trees. • During the Industrial Revolution, pollution caused trees to become darkened with soot. • More and more dark moths were seen in the peppered moth population. • After antipollution laws were passed, the soot disappeared. • Light moths increased in number. The dark moths have all but disappeared.
  • 41. History of Science: The Peppered Moth • Kettlewell's experiments confirmed that natural selection was responsible for changes in coloration in peppered moth populations. • Kettlewell released and recaptured marked moths. He recaptured more dark moths in polluted habitats and more light moths in unpolluted habitats. • Kettlewell also placed moths on trees and filmed birds eating the moths. Birds ate more light moths in polluted habitats and more dark moths in unpolluted habitats. • Challenges to Kettlewell's work resulted in his experiments being repeated by Michael Majerus. Kettlewell's results were confirmed.
  • 42. Science and Society: Antibiotic-Resistant Bacteria • Antibiotic resistance has become a serious health issue. • Antibiotic resistance is the result of natural selection. • When a patient takes a course of antibiotics, a few naturally resistant bacteria may survive the treatment. These reproduce. Eventually, strains of bacteria exist that cannot be controlled by the antibiotic. • All antibiotic use contributes to antibiotic resistance. • We must learn to take antibiotics only for bacterial infections, and then to complete the course of treatment. • Antibiotics should not be used to promote the growth of livestock.
  • 43. Science and Society: Antibiotic-Resistant Bacteria • Ways to slow the development of antibiotic resistance in bacteria: – Take antibiotics only when needed. – Take the entire course of antibiotics. – Use antibiotics responsibly in agriculture.