Download Evolution

What is Evolution?
Evolution- the genetic change of
populations over time
Population- group of organisms of the
SAME species that occupies certain area
Species- organisms that can interbreed
and produce FERTILE offspring
– Ex) populations in Sauerman Woods Crown
Point
-whitetail rabbits
-sparrows
-deer
-squirrels
Liger (lion and tiger)-infertile
Cama (camel and llama)-infertile
How Do We Know Populations
Evolve?
Population Sampling- technique uses part
of population to represent whole
population
Capture 100 random rabbits
– These rabbits are a representation of all the
rabbits in the area.
– We can study many things within this group…
Genetics of the Population…
Gene Pool- all of the
genes of every individual
in population sample
Frequency- how often
something occurs
Population genetics
involves studying the
frequency with which
certain alleles occur in a
population’s gene pool
In 50 years, will the 
allele frequencies be the
same?
Hardy-Weinberg
• Hardy-Weinberg Equilibrium Principle – frequencies
of the dominant and recessive alleles in a population
change in time due to 5 things:
• Mutations
• Migration
• Natural selection (survival of fittest)
• Small population
• Non-random mutation
• If these things occur, then the frequencies change
and a population evolves
History of Evolutionary Thought
Before 1850, most people believed…
– Earth formed by supernatural events and never
changed
– Earth only a few thousand years old
– Each species was made to fit its environment
– Species never changed and did not go extinct
Early Scientists’ Ideas
Darwin deserves credit for the Theory of
Evolution as we know it today
He was not the first to come up with the idea:
– Carl Linnaeus proposed a new system of
organization for plants and animals based on their
similarities (noticed relationships)
– Erasmus Darwin considered how organisms could
evolve through mechanisms such as competition
– Jean-Baptiste Lamarck presented evolution as
occurring due to environmental change over long
periods of time
Carl Linnaeus
Developed a classification
system for the huge variety of
living things he found
– Wrote book Systema Naturae
in 1735 to reveal his
classification system
– My closet!
– There are currently 1.9 million
species that have been
identified using his method
– Linnaeus’s system of classification
reflects evolutionary relationships
Jean Baptiste Lamarck
–
–
–
–
A French naturalist who proposed that
populations of species evolve
His idea proposed:
Changes in an environment cause an
organism’s behavior to change, leading to
greater use or disuse of a structure or organ
The organism would pass on these acquired
changes to its offspring, so a species would
change in time
Idea called “Evolution by inheritance of
acquired characteristics”
Wrong on several accounts
Charles Darwin
At 22, was invited to sail on the
“HMS Beagle”
– Was going to school to be a
minister-believed God created
each species to match its habitat
and they never changed
– Thought Earth was about 6,000
years old and didn’t change, just
like everyone else
Darwin’s Observations
One place of note that
he visited was the
Galapagos Islands
During journey, he made
observations and
recorded them in a
journal
Darwin observed fossil
and geologic evidence
supporting an ancient
Earth
Darwin’s Finches
When Darwin traveled to the Galapagos he
took interest in the finches
He noticed the finch species on the islands
were different, but all resembled one from S.
America
Darwin thought some migrated and new
species evolved
Darwin’s Finches
This is what Darwin
proposed:
– Finches migrated from
South America to the
islands
– Populations on different
islands adapted to
different environments and
food sources they found
– Those that could survive
passed on their genes
– Those that couldn’t survive
perished
Darwin’s Finches
Over time different
mutations accumulated
in the different finch
populations on the
different islands
The populations
diverged, or became
more and more
different from each
other
Darwin’s Finches
The populations on the islands became so different
they no longer mated if they met
Several new finch species evolved from a common
ancestor from S. America
This is an example of macroevolution
Recent finch
research
Speciation
Geographical isolation- members of a population
are separated geographically
– Major step that leads to speciation
– Due to volcanoes, earthquakes, flooding, etc.
– Can lead to divergence and then speciation
Artificial Selection
Artificial selection- human intervention in animal or
plant reproduction to ensure that certain desirable
traits are passed on
Instead of NATURE selecting which traits are
favorable, HUMANS selectively breed those animals
with favorable traits
Ex. dogs or racehorses
Darwin bred pigeons to
explore this idea
Darwin’s Results
In 1859, Darwin published The
Origin of Species
His book stirred up controversy
Idea called “Evolution by natural
selection”
Darwin Video
Darwin’s Book Explained Natural
Selection
Natural selection- organisms best suited to
their environment survive and reproduce
–
–
–
Darwin’s proposed mechanism of evolution
Survival depends on the particular environmental
conditions a species finds itself in—nature!
If the environment changes, so do the populations
that live there
Adaptation- using inherited genetic
characteristics to increase chance of survival
in new environment
Natural Selection and Salamanders
Natural Selection
Three conditions necessary for natural
selection to occur:
– Genetic variation: Individuals within a population
must be genetically different
****Random mutations are the raw material for
evolution to occur!!!!!!!
– Overproduction of offspring: More organisms are
born than can survive
– Differential reproduction: Certain traits enable
individuals to survive and have more offspring
than others
Result of Natural Selection
- Genes that help a population survive in their
conditions stay in their gene pool, while
“unfavorable” genes gradually decrease in
frequency
- This causes changes in the genetics of
populations EVOLUTION!!!!!
- As new mutations accumulate over a long time,
the new populations no longer can mate with the
original they started as. New species have
formed!
- Natural Selection Animation
Whose idea for
evolution is this?
What We Know Now
Evolution is a Scientific Theory
Not a hypothesis, or an
educated guess, or a
“theory” in layman’s terms
Unending amount of
evidence to support it and
NONE to reject it
Evolution is called “the unifying
principle of Biology”
Isn't Evolution JUST a Theory?
Types of Evolution
Evolution - genetic change of a population of
organisms over time descent with modification
Microevolution:
Small genetic changes of a population
Shorter amount of time
Bengal tiger simulation was
microevolution
Types of Evolution
MACROevolution-When
new species are formed
over long periods of time
– Due to tremendous
amounts of
accumulated genetic
changes in a
population
– Speciation- formation
of new species due to
accumulated
microevolution and
mutations
How does macroevolution work?
dibosirdsaur
GEOGRAPHIC ISOLATION
dibosirdsaur
dibosirdsaur
10 million years of accumulated mutations
diosirdsaur
ibosirdsaur
10 million years of accumulated mutations
diosirdsaur
iboirdsaur
10 million years of accumulated mutations
dinoirdsaur
boirdsaur
10 million years of accumulated mutations
dinordsaur
boirdsur
10 million years of accumulated mutations
dinodsaur
boirdsu
10 million years of accumulated mutations
dinodsaurs
boirds
10 million years of accumulated mutations
DINOSAURS
BIRDS
EVOLUTION
by natural selection
Microevolution
Changes
in gene frequencies
in a population
Shorter times
Examples:
Peppered moth
and Bengal tiger
MACROevolution
Accumulated
microevolution and
mutations to form
whole new species
Longer times
Examples:
Darwin’s finches and
geographical isolation
Evidence for Evolution
Three types of evidence:
– Fossils
– Anatomical
– Molecular
Fossil Evidence
•
Fossils- any traces of dead organisms
–
–
–
–
dinosaur bones
insects trapped in tree sap
leaf impressions
footprints
Fossil Evidence
•
Transitional species- species that have
been found in the fossil record that are
intermediates between two other species
in the evolutionary process
–
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Radiometric dating- a dating technique that
measures amount of radioactive material in a rock
or fossil
Relative dating- a dating technique that estimates
the date of a fossil by relating it to the age of the
layers of rock around it
Fossil Evidence
• To fossilize an
organism must be
buried by sediment
– In swamps, mud, tar
pits, or the ocean
bottom
– Hard stuff fossilizes
(bones, nails)
– Radiometric and
relative dating are
used to find out how
old the fossil is
Relative
Dating
Radiometric
Dating
Fossil Evidence
•
Fossils show:
–
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Life has been around for millions of years
Transitional species link older to newer species
– Darwin proposed the idea of transitional species,
though he had no evidence
– Today we have evidence:
• Archaeopteryx
• Tiktaalik Fossil, etc.
• Whales
Fossil Evidence-Archaeopteryx
WINGS
BEAK
Fossil Evidence
• Whales--60 million years of
evolution
– Descended from 4-legged wolflike animals that were also
ancestors to cows and horses
– Fossil evidence shows slow loss
of legs
– Pelvis still remains with no rear
legs
Anatomical Evidence
• Anatomical evidence- evidence for evolution
which is based on similarities and differences
between the physical structures of different
species.
• What can we tell about the relatedness of the
three species below?
Anatomical Evidence
• Homologous structures-Bone structure the
same (homo) but not function
–Bird wing, dolphin fin, and a human arm
–Function these structures is not the same!
–Show that these species shared a common
ancestor
–Similar structures resulted from accumulated
mutations and modifications
Homologous Structures
Anatomical Evidence
• Analogous structures- Bone structure different but
serve the same function
–Function = flight
–Butterfly wing, bat wing, fly wing
–These structures, although they have the
same function, are not built the same!
–Show different species evolved structures
with similar function through different
evolutionary pathways
–EVOLUTION IS NOT RANDOM!
Anatomical Evidence
Anatomical Evidence
•
Vestigial structuresstructures that no
longer serve a function
• These structures are
the remnants of an
evolutionary past and
show common anatomy
with other species
Molecular Evidence
•
Molecular evidenceevidence concerning the
comparison of DNA and
protein molecules between
species
• Ultimate tools for
scientists studying
evolution
• Same genetic basis
for all organisms: A,
C, T, and G shows we
are all related
Molecular Evidence
• Mutations and sexual
reproduction are a cause of
variation in a species’ DNA
• DNAmRNAprotein
– Transcription- copying the DNA
code into mRNA
– Translation- converting the code
of mRNA into a long chain of
amino acidsprotein
– Differences in DNA are seen in
differences in protein and
therefore, traits
Molecular Evidence
• Species with more similar DNA
are more closely related on the
evolutionary tree
– Less time since they
split to accumulate
mutations (and,
therefore, differences)
– Common ancestorany species in the
past from which two
or more related
species has evolved
– Evidence for Evolution
= speciation event
= mutation
• Earth is estimated to be about 4.6 billion
years old
• Atmosphere was harsh
– Very Hot
– Lots of water vapor
– Volcanoes
– NO BREATHABLE OXYGEN GAS!
– CO2, ammonia, methane present
Finding Evidence of Early Life
Stromatolites
 Scientists had hard time
finding evidence of early
life
 45 years ago we found out
why….
 Most ancient life was
microscopic=microfossils in
stromatolites
 1st organisms to evolve
were prokaryotes
 Oldest microfossil3.5
billion years old!!
Cyanobacteria fossil about
1,000,000,000 (1 billion)
years old found in stromatolites
How did life begin?
1.)Extraterrestrial origin
2.)Creation—”divine forces”
3.)From non-living matter
(“Chemical Evolution”)-Organic compounds
assembled creating 1st
bacterial cell
Early Earth’s
atoms and
molecules
Life’s Chemicals:
Proteins,
Lipids, Carbs,
Nucleic Acids
First
Prokaryotic
Cells
Origin of Life’s Chemicals
 Miller-Urey Experiment
 Hypothesis: Can organic
compounds form in early
Earth conditions?
Experiment recreated
atmosphere of early Earth
Results: building blocks of
life were formed
Amino acids (proteins)
Nucleotides (DNA, RNA)
Lipids
Carbohydrates
Origin of Life’s Chemicals
 The first genetic material was RNA
Earth’s early surface was
inhospitable due to immense UV
radiation that destroys nucleic acids
Deep sea vents may have provided
sheltered location for nucleic acids,
as well as life, to evolve
Oldest living prokaryotes found
there today…
RNA can form under conditions
similar to deep sea vents
Life’s Chemicals:
Early Earth’s
Proteins,
atoms and
Lipids, Carbs,
molecules
Nucleic Acids
Miller
Urey and
deep sea
vents
First
Prokaryotic
Cells
Origin of Cells
• Some molecules can
spontaneously form into
droplets and hollow spheres
• Solution with lipids and
proteins will self assemble
into a lipid bilayer like a cell
membrane
• First cell membrane and
beginning of prokaryotic life
took 1 billion years
Life’s Chemicals:
Early Earth’s
First
Proteins,
atoms and
Prokaryotic
Lipids, Carbs,
molecules
Cells
Nucleic Acids
Miller
Self
Urey and
assembly and
deep sea
1 billion
vents
years
Road to Modern Organisms
1st life was bacteria unicellular prokaryotes
Cyanobacteria- photosynthetic blue-green prokaryotes
later changed Earth’s atmospherereleased O2!
2nd was unicellular eukaryotes Endosymbiotic
Theory
3rd was multicellular eukaryotic organisms
Endosymbiotic Theory—3min
How Modern Day Biologists
Classify
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•
•
1. Comparing anatomy (physical traits)
2. Looking at genetic similarities & differences
3. Biochemical make-ups
4. Behavioral similarities
Origin of Life Video
Cladograms
• Cladogram- a branching diagram that shows
evolutionary relationships
• We use taxonomy – the science of classifying
living things, to help us determine the
cladogram
Writing Scientific Names
• Binomial nomenclature- unique 2-word
Latin naming system used by scientists
• 1st word is the genus, 2nd is the species
– Genus is always capitalized
– Species is always lower case
– The whole name is underlined if
written or italicized if typed
• Example: Homo sapiens:
– Homo = genus
– sapiens = species
– Common name = humans
Scientific Naming Examples
• Genus- group of organisms that share
similar characteristics
• Species- group of organisms that can
successfully breed within their group,
but not others
– Panthera leo-lion
– Panthera pardus-leopard
6 Kingdoms
• There are six kingdoms all living
things are classified into:
– Animals
– Plants
– Fungi
– Protists
– Eubacteria
– Archeabacteria
Classification
• Scientists have determined
seven levels of
classification:
– Kingdom = Kings
– Phylum = Pass
– Class = Classes
– Order = to Order
– Family = Families
– Genus = and their Good
– Species = Sons around
Classification of Modern
Humans
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•
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Kingdom = Animalia
Phylum = Chordata
Class = Mammalia
Order = Primates
Family = Hominidae
Genus = Homo
Species = sapiens
Evolution of Primates
• Primate- mammal with 5 flexible fingers
• Earliest dwelled in trees-arboreal and evolved special
adaptations for this:
• Opposable thumb….Why?
• Binocular vision- eyes in front of head in which
field of vision of eyes overlap—depth
perception….Why?
• Rotating Shoulders
2 Types of Primates
• Primates are divided into 2 groups:
1. prosimians and 2. anthropoids
• Prosimians- nocturnal
primates that were the
first to evolve
– i.e. Loris and Bush Baby
– 30-40 million year fossils show
they were common
– Nighttime hunters…How can you
tell?
2 Types of Primates
• Anthropoids- day active primates
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Monkeys, apes, and humans
Smaller eyes
Color vision
Larger brains
Replaced prosimians rapidly
2 Types of Primates
• Anthropoids—3 categories
– Monkeys
• Have tails
• Old World—Asia and Africa
• New World—Central and S. America
– Apes
• NO TAILS
• Larger brains than monkeys
• Chimps, gibbons, orangutans,
bonobo, etc.
– Humans
• Our closest genetic primate
relative is?
Evolution of Humans
• Vocab:
– Bipedal- walk upright on two legs
– Hominid- bipedal primates such as humans
and their closest fossil relatives
Hominids
• Hominids are the ONLY bipedal primates:
– Locking knee joints
– Spine enters skull at
bottom of head
– Femurs (thigh bone)
tapers in
– Big toe in line with
others
Laetoli Footprints
Hominid vs. Chimpanzee
• Chimps most closely related primate to humans—
95% similarity in the sequence of our genes!
• Differences:
– Human’s jaw arc shaped with smaller canines; chimps’ are
U shaped with larger canines and larger gaps.
Hominid vs. Chimpanzee
– Hominid spine S–
chimps’ is C shaped
– Hominid pelvis is
bowl-shaped, chimps’
long
– Hominid thigh bones
taper in—chimps’ out
– Human Evolution
Video Clip
Early Hominids
• Darwin’s Descent of Man
– 1871
– African apes are close genetic
relatives of modern humans
– Said fossilized remains of ape
and human common ancestor
should be found in Africa
Early Hominids
•
Genus Australopithecus
A. afarensis
•
Genus Homo
Time
Homo habilis
Homo erectus
Homo sapiens
NOT A COMPLETE LIST! THERE ARE
OTHERS!
Australopithecus
• Genus Australopithecus
– LucyAustralopithecus afarensis
– Fossil found in Africa
– They were hominids
• Shape of pelvis and femurs
showed they were bipedal.
• Locking knee joints
– Short—3’6’’
– Brain size of chimps
– Jaws more rounded than apes
– Teeth like humans
LUCY
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•
•
3.5 million years old
40% complete
Female
Showed us:
– Walked upright first
– Brain size grew
LATER.
SKULLS
A. afarensis (Lucy) Homo sapien
•
SKULLS
Lucy had a small skull like an ape, but she
wasn’t one
LUCY
APE
APES
Homo sapiens
transitional species
Homo erectus
Homo habilis
Australopithecus afarensis
common ancestor to
ape and H. sapiens
Homo habilis
• Means: “handy man”
• Small structure like
Lucy
• Skull 2X’s the size of
Lucy
• 2- 1.8 mya in Africa
• Tools made of bone
and stone
Homo erectus
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•
•
•
•
•
Peking man
Africa / Asia / Europe
Larger than H. habilis
Larger brain
Excellent tools, used fire
1.5 mya – “immediate”
ancestor
Where Did H. sapiens evolve?
• Out of Africa
hypthothesis- idea like
Darwin’s which states
H. sapiens evolved IN
Africa and spread to H..sapiens
rest of world
• Out of Africa hypothesis H. erectus
supported by fossils of
modern-like humans
found in Africa
Early H. sapiens
• Homo neanderthalensis discovered in Neander Valley in
Belgium
• Massive skulls and
protruding brows
• 400,000-100,000 years ago
Early H. sapiens
Great controversy: did
they die off (genes no
longer) or did they
interbreed with us so their
genes are still in our gene
pool?
Modern H. sapiens
probably evolved in Africa
and replaced Neanderthals.
Mated????
APES
Homo neanderthalensis
transitional species
Homo sapiens
Homo erectus
Homo habilis
Australopithecus afarensis
common ancestor to
ape and H. sapiens
Recent Discoveries
• 2009 Recent analysis of
Ardipithecus ramidus… aka
“Ardi” found in 1994
– A hominid with opposable big
toes like chimps and apes
– 1.2 million years OLDER than
Lucy, and our oldest known
common ancestor with other
primates (4.4 mya)!
– 47 inches tall
– Show that chimps have
actually evolved MORE than
humans since our common
ancestor
Mated????
APES
Homo neanderthalensis
transitional species
Homo sapiens
Homo erectus
Homo habilis
Australopithecus afarensis
common ancestor to
ape and H. sapiens
ARDI?????
Evolution Summary
• The Theory of Evolution by Natural Selection
holds the high status of near certainty: it’s a
scientific theory
• There are no observations of life, living or
extinct, that evolution cannot explain
• Why is evolution controversial anyway?