Transcript Chapter 2 the Development of Evolutionary Theory

Chapter 2
Development of Evolutionary Theory
A Brief History of Evolutionary Thought
 Natural Selection in Action
 Constraints on Nineteenth-Century
Evolutionary Theory
 Opposition to Evolution
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Pre-scientific Views
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Statis - The world is fixed and unchanging
The great- chain of being - life is arranged
from the simplest to most complex.
The earth is “full” and nothing could be added.
Grand Design - The world is the result of
God’s design.
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 rather than
fixity.
Keppler, Descartes and Newton established
the laws of physics, motion and gravity.
The Path to Natural Selection
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John Ray provided the first definition of the
concept of species and genus.
Carolus Linnaeus developed a system of
classification and laid the basis for taxonomy.
The Path to Natural Selection
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Comte de Buffon stressed the importance of
change in the universe and recognized the
environment as an agent of change.
John Baptiste Lamack was the first scientist
to produce an explanation for the evolutionary
process.
The Path to Natural Selection
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Georges Cuvier introduced the concept of
extinction and the theory of catastrophism.
Charles Lyell developed the theory of
uniformitarianism.
Thomas Malthus wrote about the relationship
between food supplies and population
increase.
Charles Darwin (1809-1882)
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Many ideas were formed during the voyage of
the HMS beagle.
Saw biological variation within a species as
critically important.
Recognized the importance of sexual
reproduction in increasing variation.
Alfred Russell Wallace (1823-1913)
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A naturalist who worked in South America and
Southeast Asia.
Published article suggesting species were
descended from other species and new
species were influenced by their environment.
Processes of Natural Selection
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Species can produce offspring at a faster rate
than food supplies increase.
In each generation, more individuals are
produced than can survive.
Individuals that possess favorable traits are
more likely to survive and produce offspring
than those who do not.
Processes of Natural Selection
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Traits are inherited and passed on to the next
generation.
Over a period of time, variations accumulate 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 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.