Theory of Evolution
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Transcript Theory of Evolution
Key Terms
Biogenesis:
All living things come from other living things
Makes sense to us, but prior to the 17th century they had
other ideas
Spontaneous Generation:
Living things could arise from nonliving things
Ideas from the Past
Francesco Redi (1626-1697):
Observed fundamental forms of flies
Found that they form from maggots
Previously thought that flies spontaneously generated
from rotten meat
Ideas from the Past
During this time scientists using microscopes thought
that microorganisms arose spontaneously from a “vital
force” in the air
Lazzaro Spallanzani (1729-1799): text p. 280
Found that microorganisms come from other
microorganisms
Used broth: Control group & Experimental Group
Many scientists did not accept his conclusions
Ideas from the Past
Mid-1800s, controversy over spontaneous generation
raged on
Prize was offered to who ever could clear up the issue
Louis Pasteur (1822-1895):
Answered Spallanzani’s experiment
Used broth and curved-necked flask
Section 14.2
Earth’s History
Formation of the Earth
5 billion years ago our solar system formed
Age of the earth is more than 4 billion years
Radiometric Dating
Determines the age of materials
Use radioactive isotopes and their rate of decay
Carbon 12 – STABLE
Carbon 14 – UNSTABLE – decays at a certain rate
Half-life = length of time it takes for one-half of any size
sample of an isotope to decay to a stable form
Measured against the amount of another stable substance
(Carbon – 12)
How?
When an organism dies, its uptake of carbon stops
Carbon-14 decay continues & Carbon-12 remains constant
Radiometric Dating & Half-Lives
Carbon-14 = 5,730 years
Uranium-235 = 704,000,000 years
Potassium-40 = 1,250,000,000 years
Uranium-238 = 4,500,000,000 years
Earth’s History
Miller-Urey Experiment: tested the hypothesis
Some molecules, including amino acids, did form
However: now know that the early atmosphere was CO2,
N, water vapor, & high O2…this prevents organic
molecule production
First Cells
Lack evidence, and can only make inferences
Anaerobic, heterotrophic prokaryotes
First Eukaryotes
Formed from prokaryotic cells that formed a
mutually beneficial relationship
Endosymbiosis: smaller aerobic prokaryote was
engulfed by and began to live and reproduce inside
of a larger, anaerobic prokaryote
Later evolved into mitochondria and chloroplasts
Evidence for this: replicate independently, circular DNA
Idea of Evolution
Charles Darwin (1809-1882)
Traveled the world & noticed similarities & differences
among many organisms
Was convinced that organisms changed over time
Idea of Evolution
Evolution: development of new types of organisms
from preexisting types of organisms over time
Heritable change in characteristics w/in a pop. from one
generation to the next
Darwin’s Theory
Developed to explain how evolution occurs
Idea of Evolution
Ideas of Darwin’s Time
Species were permanent & unchanging
Earth’s age only 1000’s of years old
Idea of Evolution
Ideas About Geology
Studied Strata, or rock layers
Lower strata=older rock/ Higher strata=younger
Different strata holds different organisms
Georges Cuvier: Catastrophism, idea that sudden
geologic catastrophes caused extinctions
Charles Lyell: Uniformitarianism, processes that have
changed the shape of the Earth’s surface in the past
continue to work
Sedimentary Rock
Idea of Evolution
Lamarck’s Ideas on Evolution
Supported Darwin
Idea that simple organisms could arise from nonliving
matter
Life developed from simple to complex
Acquire traits during lifetime as a result of experience or
behavior––> offspring
Inheritance of acquired characteristics
Darwin’s Ideas
Darwin & Alfred Wallace formed new theory on how
evolution take’s place
Presented to scientists in London after voyage around
the Earth
Published: On the Origin of Species by Means of Natural
Selection
Evidence for evolution
Explain variety & distribution of organisms
Darwin’s Ideas
Descent w/ Modification
Species descend by reproduction from preexisting
species
Argued that ALL species had descended from only ONE
or a FEW original kinds of life
Example: Galapagos Islands
Finches: 13 species descended from 1 common ancestor
Darwin’s Ideas
Natural Selection
4 Main Parts of Darwin’s Reasoning
Overproduction: More offspring produced than survive
Genetic Variation: Individuals have different traits
Occasionally new traits may appear in a population
Struggle to Survive: individuals compete to survive &
reproduce
Thomas Malthus: environment limits populations
Variations improve or reduce chances
Adaptation = trait that makes an individual successful
Differential Reproduction:
Best adaptations = survival
Adaptations become more frequent & populations differ
Darwin’s Ideas
Natural Selection
Accounts for descent w/ modification, as species
become better adapted to different environments
Nature changes species by selecting traits
Fitness = measure of an individual’s hereditary
contribution to the next generation
Ability to survive and reproduce
Evidence of Evolution
15-2 Questions
1.
The wing of a bat and the foreleg of an alligator are
A.
B.
C.
D.
2.
Analogous features.
Homologous features
Vestigial features.
Artificially selected features.
Features that were useful to an ancestral organism but are not useful to a
modern organisms that inherited them are said to be?
A.
B.
C.
D.
Analogous.
Homologous.
Vestigial.
Artificially selected.
15-2 Questions
3.
According to the principle of superposition, the lowest layer in a cross
section of a rock sequence
A.
B.
C.
D.
4.
Which of the following is an impediment to understanding the evolutionary
history of all organisms?
A.
B.
C.
D.
5.
Is the most recent
Is the oldest
Has the fewest fossils
Contains only the fossils of burrowing animals
Presence of vestigial structures
Lack of transitional fossils
Lack of homologous structures
Presence of analogous structures
Fossils are
A.
c.
Remains or traces of preexisting organisms
Deeply buried sedimentary rock strata
All extinct organisms
D. From animals, not plants
B.
The Fossil Record
What is a fossil?
Remains or traces of an organism that died long ago
Formed under many different conditions
Different organisms, different times & places
Some of the most powerful evidence for evolution
The Fossil Record
Age of Fossils
Nicolaus Steno (1638-1686)
Principle of superposition:
Rock strata at a location have not been disturbed, the lowest
stratum was formed before the strata above it
Geologists in 1700s & 1800s compared strata from
different places & compared fossils found in different
strata
Put together the geologic time scale – timeline for the order of
organisms
The Fossil Record
Age of Fossils
Fossil’s relative age: age compared to that of other fossils
Determined by referring to the geologic time scale and to records
of known fossils
Absolute age: time since the formation of the rock
Determined by radiometric dating
Use relative and absolute dating to make the history of
life on earth as precise as possible
Fossil record is incomplete––not ALL organisms have left fossil
evidence, only form by rare events
The Fossil Record
The Distribution of Fossils
4 Inferences that can be made
Different organisms lived at different times
Today’s organisms are different from those in past
Fossils found in adjacent layers are more similar than fossils
found higher or lower in strata
By comparing fossils from all over the world, we can infer when
and where organisms existed
The Fossil Record
Transitional Species
Infer that species have differed in a gradual sequence of
forms over time
Based on Transitional Species, which have features that are
intermediate b/w those of hypothesized ancestors and later
descendent species
Hypothesis of whale evolution is an example
Other groups of organisms for which no transitional species
have been found as fossils
Biogeography
Study of the locations of organisms around the world
Darwin & Wallace saw evidence of evolution in
distribution of organisms
Closely related organisms, but occupied different habitats
Unrelated organisms, but had similar adaptations in similar
environments that were far apart
Example: Australian Mammals
Anatomy & Embryology
Anatomy: study of the body structure of
organisms
Embryology: study of how organisms develop
Descent w/ modification also predicts the findings
of anatomy & embryology
Bones in the forelimbs of humans, penguins, alligators,
and bats
Explanation: early ancestor shared by all these
organisms had a forelimb w/ a similar bone structure
Anatomy & Embryology
What happened?
Generations passed, & diff. populations of descendents
adapted to diff. envirn.
Bones inherited from ancestors became modified for
different tasks
Homologous Structures: anatomical structures that
occur in diff. species & that originated by heredity
from the most recent common ancestor
Anatomy & Embryology
Analogous Structures: closely related functions
but do not derive from the same ancestral
structure
Ex: birds, bats and moths have wings, but they have
very diff. underlying structures
Wings evolved independently in these animals
Vestigial Structures: structures that seem to
serve no function , but that resemble structures
w/ functional roles in related organisms
Ex: human tailbone––animal tail; whale pelvic bone;
human appendix
Anatomy & Embryology
Development of Animal Embryos
Some stages of vertebrate embryo development are very
alike
Similarities fade as development proceeds
Possible answer––vertebrates share a common ancestor
Biological Molecules
Organisms that share many traits––>more recent
common ancestor than those that share fewer
traits
Darwin predicted this through anatomy
Modern studies of biological molecules support this
DNA & RNA are molecular basis for inheritance of traits
DNA affects traits encoding the amino acid sequences that form
proteins
Developing Theory
Hypotheses & theories of evolution are continually
being formed, challenged, and revised
Many aspects are poorly understood & some
observations remain unexplained
Can never be “proven”, but is widely accepted &
applied by scientists b/c it explains the broadest
range of observations & makes useful predictions
Convergent Evolution
Divergent Evolution
Artificial Selection
Chapter 16
Genetic Equilibrium
Variation of Traits w/in a Population
Population Genetics: genetic study of evolution
Microevolution: evolution at the genetic level, where a
change in the collective genetic material of a population
occurs
Vary in observable traits
Genetic Equilibrium
Variation arises from:
Mutation
Recombination
Random pairing of gametes
Genetic Equilibrium
Gene Pool: total genetic info available in a population
Allele frequency: how often an allele will show up
Certain allele number / total number of alleles
Phenotype frequency: how often a phenotype shows
Number of indiv. w/ phenotype / total number of indiv. in the
population
Genetic Equilibrium
Hardy-Weinberg Genetic Equilibrium
Genotype frequencies in a population tend to remain
the same from generation to generation UNLESS acted
on by outside influences
No mutations
No individuals enter or leave the population
Large population
Random mating
Natural selection does not occur
Disruption of Genetic Equilibrium
Mutations
Exposed to mutagens…increase mutations
Creates new alleles for a trait
Most are harmful…some beneficial
Disruption of Genetic Equilibrium
Gene Flow
Size of population needs to remain constant
Immigration: movement into a pop.
Emigration: movement out of a pop.
Process of genes moving from one population to another
Migration, dispersal of seeds/spores
Disruption of Genetic Equilibrium
Genetic Drift
Allele frequencies in a population change as a result of
random events, or chance
Mechanism for evolution of a new species
Graph page 322
Disruption of Genetic Equilibrium
Nonrandom Mating
Sexual Selection
Females choose the males based on certain traits
Ex: birds
Natural Selection
Stabilizing Selection: average form of a trait have the
highest fitness – medium fish
Disruptive Selection: either extreme variation have
greater fitness – very small/very large fish
Directional Selection: more extreme form has greater
fitness – very large fish
Question #1
Scientists
have
estimated the age
of Earth to be
a.
b.
c.
d.
about 10 billion years old.
100,000 years old.
about 4.6 billion years old.
about 4.6 million years old.
Question #2
What
theory
proposes a method
for the evolution
of photosynthetic
eukaryotic
organisms from
prokaryotes?
a)Chemosynthesis
b) RNA replication
c) radioactive decay
d) endosymbiosis
Question #3
What
is the idea
developed by
Charles Lyell
stating that the
geologic processes
that shaped the
Earth in the past
continue to operate
today?
a)Catastrophism
b) uniformitarianism
c) inheritance of acquired
characteristics
Question #4
What
is the process
called by which
different species
evolve similar
traits?
a)adaptive
radiation
b) divergent evolution
c) Coevolution
d) convergent evolution
Question #5
Strong
evidence
for evolution
comes from:
a)phylogenetic
trees.
b) nuclear physics.
c) the fossil record.
d) works of philosophy.
Question #6
Eukaryotes
may
have evolved
from:
a)prokaryotes
and
engulfed small
anaerobic prokaryotes.
b) eukaryotes and
engulfed small aerobic
prokaryotes.
c) cyanobacteria.
Question #7
The
evolutionary
pattern
illustrated by
the
finch species on
the Galapagos
Islands is an
example of:
a)coevolution.
b) convergent evolution.
c) divergent evolution.
d) artificial selection.
Question #8
a.
b.
c.
d.
According to Darwin, evolution occurs
In response to use or disuse of a characteristic
Because of catastrophic geologic events
By natural selection
Within an individual’s lifetime
Question #9
a.
b.
c.
d.
The inference that evolution occurs gradually
over time,
Is not supported by any fossil evidence
Is know as coevolution
Is supported by many transitional forms in the fossil
record
Was proposed by Lyell
Question #10
a.
b.
c.
d.
Natural selection causes
Changes in the environment
Plants and animals to produce more offspring than
can survive
Changes in the frequency of certain adaptations in a
population
Genetic variation w/in populations
Question #11
a.
b.
c.
d.
The similarity in the body shape of a whale and
of a fish is an example of
Divergent evolution
Convergent evolution
Coevolution
Vestigial structures
Question #12
a.
b.
c.
d.
Which of the following must exist in a
population in order for natural selection to act?
Genetic variation
Overproduction
Struggle to survive
All of the above
Question #13
a.
b.
c.
d.
The scientist who proposed that individuals
could pass on traits acquired during their
lifetime was
Lamarck
Darwin
Cuvier
Lyell
Question #14
a.
b.
c.
d.
Which of the following is an acquired human
characteristic?
Number of bones in the hand
Eye color
The presence of a tailbone in humans
Large muscles from weight lifting
Question #15
a.
b.
c.
d.
Which of the following is an impediment to
understanding the evolutionary history of all
organisms?
Presence of vestigial structures
Lack of transitional fossils
Lack of homologous structures
Presence of analogous structures