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Chapter 15
Section 1 History of Evolutionary
Thought
Objectives
• Define the biological process of evolution.
• Summarize the history of scientific ideas about evolution.
• Describe Charles Darwin’s contributions to scientific thinking
about evolution.
• Analyze the reasoning in Darwin’s theory of evolution by natural
selection.
• Relate the concepts of adaptation and fitness to the theory of
natural selection.
Chapter 15
Section 1 History of Evolutionary
Thought
The Idea of Evolution
• Charles Darwin is one of the 1st people to study
evolution of different species. He came up with one
of the most important theories in Biology because of
his studies.
• Evolution is the process of change in the inherited
characteristics within populations over generations
such that new types of organisms develop from
preexisting types.
Chapter 15
Section 1 History of Evolutionary
Thought
The Idea of Evolution, continued
• Ideas of Darwin’s Time
– Scientific understanding of evolution began to
develop in the 17th and 18th centuries as
geologists and naturalists compared geologic
processes and living and fossil organisms around
the world.
Chapter 15
Section 1 History of Evolutionary
Thought
Darwin’s Ideas
• 1859 – Darwin published On the Origin of Species by
Means of Natural Selection
– He had two main goals of writing this book: he
wanted to present the large amount of evidence
that evolution occurs and he wanted to explain the
variety and distribution of organisms on Earth in
terms of natural processes that are observable
every day
Chapter 15
Section 1 History of Evolutionary
Thought
Darwin’s Ideas
• His book pointed out many different ideas/issues,
here are some of the most important ones:
– Idea that species change slowly over time
– Idea that some organisms reproduce at different
rates than others
– Idea that some species become better suited to
their environment than others
Chapter 15
Section 1 History of Evolutionary
Thought
Darwin’s Voyage
Chapter 15
Section 1 History of Evolutionary
Thought
Darwin’s Ideas
• Descent with Modification
– Darwin wrote On the Origin of Species, in which
he argued that descent with modification occurs,
that all species descended from common
ancestors, and that natural selection is the
mechanism for evolution.
Chapter 15
Section 1 History of Evolutionary
Thought
Darwin’s Ideas, continued
• Natural Selection
– Organisms in a population adapt to their
environment as the proportion of individuals with
genes for favorable traits increases.
– Those individuals that pass on more genes are
considered to have greater fitness.
– Fitness is the measure of an individual’s
heredity contribution to the next generation
Chapter 15
Section 1 History of Evolutionary
Thought
Natural Selection
Chapter 15
Section 2 Evidence of Evolution
Objectives
•
Relate several inferences about the history of life that are supported by
evidence from fossils and rocks.
•
Explain how biogeography provides evidence that species evolve
adaptations to their environments.
•
Explain how the anatomy and development of organisms provide
evidence of shared ancestry.
•
Compare the use of biological molecules with other types of analysis of
evolutionary relationships.
•
Describe the ongoing development of evolutionary theory.
Chapter 15
Section 2 Evidence of Evolution
The Fossil Record
• A fossil is the remains of an organism that lived long
ago
• Evidence of evolution can be found by comparing
several kinds of data, including the fossil record,
biogeography, anatomy and development, and
biological molecules.
• Evolutionary theories are supported when several
kinds of evidence support similar conclusions.
Chapter 15
Section 2 Evidence of Evolution
The Fossil Record, continued
• The Age of Fossils
– Geologic evidence supports theories about the
age and development of Earth.
– 1669 – Danish scientist Nicolaus Steno proposed
the idea of superposition
– It states that if a rock strata at a location
haven’t been disturbed the lowest stratum
was formed before that strata above it
Chapter 15
Section 2 Evidence of Evolution
The Fossil Record, continued
• Absolute Age vs. Relative Age
– Absolute age: getting exact age of rock layers or
fossils by using techniques such as radiometric
dating
– Relative age: an age that is a comparison, by
comparing fossils or rock layers
» Mr. Kranzo is older than all of the students in this class
» No age in years will be provided, just a comparison
Chapter 15
Section 2 Evidence of Evolution
The Fossil Record, continued
• The Distribution of Fossils
– The fossil record shows that the types and
distribution of organisms on Earth have changed
over time.
Chapter 15
Section 2 Evidence of Evolution
The Fossil Record, continued
• Transitional Species
– Fossils of transitional species show evidence of
descent with modification.
• Ex. Evolutionary scientists have hypothesized that
modern marine mammals, such as whales, evolved from
early mammals in the fossil record that walked with four
legs on land
Chapter 15
Section 2 Evidence of Evolution
Evidence of Whale
Evolution
Figure 15-7 pg 304
These fossil skeletons
show a sequence of
transitional forms that
support that whales
came from four-legged
land-dwelling
mammals
Fill in the descriptors
from page 304 OYO
Chapter 15
Section 2 Evidence of Evolution
Biogeography
• Biogeography, the study of the locations of
organisms around the world, provides evidence of
descent with modification.
Chapter 15
Section 2 Evidence of Evolution
Anatomy and Physiology
• In organisms, analogous structures are similar in
function but have different evolutionary origins.
• Beak of a bird and beak of giant squid are an example,
both beaks, but evolved independently of each other
even though they are similar in function
• Homologous structures have a common
evolutionary origin.
Chapter 15
Section 2 Evidence of Evolution
Forelimbs of
Vertebrates
All of these would be
considered homologous
structures
Chapter 15
Section 2 Evidence of Evolution
Anatomy and Physiology, continued
• A species with a vestigial structure probably shares
ancestry with a species that has a functional form of
the structure.
• Ex. human tailbone, human appendix, and
pelvic bones of modern whales
Chapter 15
Section 2 Evidence of Evolution
Anatomy and Physiology, continued
• Related species show similarities in embryological
development.
• Look at Fig 15-9 pg 306
Chapter 15
Section 2 Evidence of Evolution
Biological Molecules
• Similarity in the subunit sequences of biological
molecules such as RNA, DNA, and proteins indicates
a common evolutionary history.
Chapter 15
Hemoglobin
Comparison
Section 2 Evidence of Evolution
Chapter 15
Section 2 Evidence of Evolution
Developing Theory
• Modern scientists integrate Darwin’s theory with other
advances in biological knowledge.
• Theories and hypotheses about evolution continue to
be proposed and investigated.
Chapter 15
Section 2 Evidence of Evolution
Developing Theory
• Not until the mid-1900s did scientists begin to integrate
the theory of natural selection with new understandings
of genetics. This blending has been called the modern
synthesis of evolutionary theory (MSOET)
• The MSOET predicts that:
• Closely related species will show similarities in DNA
sequences
• If species have changed over time, their genes should
have changed
• Closely related species will show similarities in amino
acid sequences
Chapter 15
Section 3 Evolution in Action
Objectives
• Compare artificial selection and natural selection.
• Explain how organisms can undergo coevolution.
Chapter 15
Section 3 Evolution in Action
Artificial Selection
• The great variety of dog breeds is an example of
artificial selection.
• Artificial selection has been used by humans to
speed up the process of divergent evolution
Chapter 15
Section 3 Evolution in Action
Artificial Selection cont.
Saint Berdoodle
St. Bernard / Poodle Hybrid
Labradoodle
Chug
Labrador Retriever / Poodle Hybrid
Chihuahua / Pug Hybrid
Chapter 15
Section 3 Evolution in Action
Coevolution
• Coevolution is the process in which 2 or more
species become more adapted over time to each
other’s presence
• Ex. Plants and their pollinators