Transcript Chapter 2 the Development of Evolutionary Theory

Chapter 2
The Development of Evolutionary
Theory
Chapter Outline
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A Brief History of Evolutionary Thought
The Discovery of Natural Selection
Natural Selection
Natural Selection in Action
Constraints on Nineteenth-Century
Evolutionary Theory
Opposition to Evolution Today
Natural Selection
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The most critical mechanism of
evolutionary change, first articulated by
Charles Darwin; refers to genetic change
or changes in the frequencies of certain
traits in populations due to differential
reproductive success between
individuals.
Fixity of Species
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The notion that species, once created,
can never change; an idea diametrically
opposed to theories of biological
evolution.
Aristotle’s Worldview
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This beautifully illustrated
seventeenth-century map
shows the earth at the
center of the solar
system.
Around it are 7
concentric circles
depicting the orbits of the
moon, sun, and the 5
planets that were known
at the time.
Pre-scientific View
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In the middle ages, the predominant world was
stasis, the world was fixed and unchanging.
The great chain of being held that life was
arranged from simplest to most complex.
It was believed that the earth was “full” and
nothing new could be added.
The world was seen as the result of a grand
design - God’s design.
Reproductively Isolated
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Pertaining to groups of organisms that,
mainly because of genetic differences,
are prevented from mating and producing
offspring with members of other groups.
Binomial Nomenclature
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In taxonomy, the convention established by
Carolus Linnaeus whereby genus and species
names are used to refer to species.
For example, Homo sapiens refers to human
beings.
Taxonomy is the branch of science concerned
with the rules of classifying organisms on the
basis of evolutionary relationships.
Evolution
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A change in the genetic structure of a
population.
Also refers to the appearance of a new
species.
Often controversial, some religious views
hold that evolutionary statements run
counter to biblical teachings.
Lamarck
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John Baptiste
Lamack was the first
scientist to produce
an explanation for the
evolutionary process.
He believed that
species change was
influenced by
environmental
change.
Cuvier
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Georges Cuvier
introduced the
concept of extinction
and the theory of
catastrophism.
Thomas Malthus
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Thomas Malthus wrote
about the relationship
between food supply and
population increase.
His essay on the
Principle of Population
led both Darwin and
Wallace to the principle
of natural selection.
Charles Lyell
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Charles Lyell
developed the theory
of uniformitarianism.
Catastrophism
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The view that the earth’s geological
landscape is the result of violent
cataclysmic events.
Cuvier promoted this view, especially in
opposition to Lamarck.
Uniformitarianism
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The theory that the earth’s features are
the result of long term processes that
continue to operate in the present as they
did in the past.
Elaborated on by Lyell, this theory
opposed catastrophism and contributed
strongly to the concept of immense
geological time.
Mary Anning
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Discovered the first
complete fossil of
Ichthyosaurus, a large
fishlike marine reptile.
She became known as
one of the world’s
leading “fossilists” and
contributed to the
understanding of the
evolution of marine life
over 200 million years
ago.
Charles Darwin
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Charles Darwin,
photographed 5
years before the
publication of Origin
of Species.
Question
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One of the world's leading "fossilists"
who contributed to the understanding of
the evolution of marine life over 200
million years was:
a) Mary Anning.
b) Lyell.
c) John Ray.
d) Darwin.
Answer: a
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One of the world's leading "fossilists" who
contributed to the understanding of the
evolution of marine life over 200 million
years was Mary Anning.
Question
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The person credited with removing the
earth as the center of the universe is:
a) Buffon.
b) Lamarck.
c) Copernicus.
d) Archbishop James Ussher.
Answer: c
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The person credited with removing the
earth as the center of the universe is
Copernicus.
Evolution Is a Theory
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The theory has been supported by a
mounting body of genetic evidence.
The theory has stood the test of time.
The theory stands today as the most
fundamental unifying force in biological
science.
The Scientific Revolution
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Discovery of the new world challenged
fundamental views about the planet.
Exposure to new plants and animals
increased awareness of biological
diversity.
The Scientific Revolution
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Copernicus challenged the idea that the
earth was the center of the universe.
Galileo’s work supported the idea that the
universe was a place of motion.
Keppler, Descartes and Newton
established the laws of physics, motion
and gravity.
Precursors to the Theory of
Evolution
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John Ray provided first definition of the
concept of species and genus.
Carolus Linnaeus developed system of
classification and the basis for taxonomy.
Comte de Buffon stressed the
importance of change in the universe and
the environment as an agent of change.
Charles Darwin (1809-1882)
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Ideas were formed while serving as a naturalist
on the voyage of the HMS beagle.
Darwin saw the importance of biological
variation within a species.
Recognized the importance of sexual
reproduction in increasing variation.
By 1844, Darwin had complete the work that he
would publish fifteen years later.
The Path of the HMS Beagle
Darwin’s Galápagos Finches
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Beak Variation
Domestic Dog Breeds
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The variation exhibited by dog breeds has been
achieved in a relatively short time through
artificial selection.
Alfred Russell Wallace
(1823-1913)
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A naturalist who worked in South America
and Southeast Asia.
Suggested species descended from other
species and new species were influenced
by environmental factors.
Presented paper on evolution and natural
selection to the Linnean Society of
London jointly with Darwin.
Contrasting Views on
Evolution
Contrasting Views on
Evolution
Question
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Darwin recognized that individuals were
unique. He realized that ________ could
explain how selection occurred.
a) variation
b) strength
c) altitude
d) time
Answer: a
• Darwin realized that variation among
individuals was how selection occurred,
ultimately causing change in species
Processes of Natural
Selection
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Species can produce offspring at a faster
rate than food supplies increase.
There is biological variation within all
species.
In each generation, more individuals are
produced than can survive.
Processes of Natural
Selection
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Individuals that possess favorable traits
or variations are more likely to survive
and produce offspring.
Environmental context determines
whether a trait is beneficial.
Traits are inherited and passed on to the
next generation.
Processes of Natural
Selection
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Variations accumulate over long periods
of time, so later generations may be
distinct from ancestral ones.
As populations respond to pressures
over time, they may become distinct
species, descended from a common
ancestor.
Natural Selection in Action
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Variation in the
peppered moth.
(a) The dark form is
more visible on the
light, lichen-covered
tree.
(b) On trees
darkened by
pollution, the lighter
form is more visible.
Question
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Selective forces come from:
a) individuals.
b) genetics.
c) populations.
d) the environment.
Answer: d
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Selective forces come from the
environment.
Evolutionary Change
Through Natural Selection
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A trait must be inherited if natural selection is
to act on it.
Natural selection can’t occur without
population variation in inherited
characteristics.
Fitness is a relative measure that changes as
the environment changes.
Natural selection can only act on traits that
affect reproduction.
Christian Fundamentalists
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Adherents to a movement in American
Protestantism that began in the early
twentieth century.
This group holds that the teachings of the
Bible are infallible and are to be taken
literally.