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
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.
Different Views of Evolution
The Path to Natural Selection
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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.
The Path to Natural Selection
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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.
Route 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.
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.
Mechanism of Natural
Selection
Development of Modern
Evolutionary Theory
Evolutionary Change
Through Natural Selection
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A trait must be inherited to have
importance in natural selection.
Natural selection cannot occur without
variation in inherited characteristics.
Fitness is a relative measure that will
change as the environment changes.