Transcript Chapter 2 the Development of Evolutionary Theory

Chapter 2
The Development of Evolutionary
Theory
Chapter Outline
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Brief History of Evolutionary Thought
Natural Selection in Action
Constraints on Nineteenth-Century
Evolutionary Theory
Opposition to Evolution
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.
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.
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.
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.
Precursors to the Theory of
Evolution
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John Baptiste Lamack was the first scientist to
produce an explanation for the evolutionary
process.
Georges Cuvier introduced the concept of
extinction and the theory of catastrophism.
Charles Lyell developed the theory of
uniformitarianism.
Thomas Malthus wrote about relationship
between food supply and population increase.
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
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
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.
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.
Quick Quiz
1. To understand the complexities of
evolution one must be well versed in
a) mathematics and statistics.
b) botany and paleontology.
c) genetics and biology.
d) anatomy and physiology.
Answer: c
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To understand the complexities of
evolution one must be well versed in
genetics and biology.
2. Genetic evidence supports evolution.
a) True
b) False
Answer: true
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Genetic evidence supports evolution
3. Darwin realized that variation among
_________________ was how selection
occurred, ultimately causing change in
species.
Answer: individuals
• Darwin realized that variation among
individuals was how selection occurred,
ultimately causing change in species
5. Natural selection acts on existing
_________________ within a species.
Answer: variation
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Natural selection acts on existing
variation within a species.