Download Chapter Ten: Principles of Evolution

Section One: Early Ideas About
Evolution
 Evolution
 The process of biological change by which descendants
come to differ from their ancestors

Scientists Involved
 Linnaeus: developed a classification system
 Species: a group of organisms so similar to one another that
they can reproduce and have fertile offspring
 Buffon: proposed that species shared ancestors
 Erasmus Darwin: proposed that all living things came from a
common ancestor
 Lamarck: said changes in the environment could change an
organism’s behavior and thus change its genetics
Section One: Early Ideas About
Evolution
 Evolution
 The fossil record set the stage
for the theory of evolution


Fossil: traces of organisms that
existed in the past
The fossil record also led to
other theories

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Catastrophism: says natural
disasters such as floods and
volcanic eruptions have
happened often during the
history of Earth
Gradualism: changes in
landforms are a result of slow
changes over a long period of
time
Uniformitarianism: the
geologic processes that shape
Earth are uniform through time
Section Two: Darwin’s
Observations
 Charles Darwin
 Observed variation among
traits in similar animals

Variation: the difference in
the physical traits of an
individual from those of
other individuals in the
group to which it belongs
 Said species somehow
adapted to their
surroundings

Adaptation: a feature that
allows an organism to better
survive in its environment

Can lead to genetic change
in a population over time
Section Two: Darwin’s
Observations
 Charles Darwin
 Found fossil evidence of
species changing over
time
 He found fossils of
marine animals in the
mountains suggesting
geological changes
through time also
Section Three: Theory of Natural
Selection
 Insights to Natural
Selection
 Artificial Selection: the
process by which
humans change a
species by breeding it
for certain traits
 Heritability: the ability
of a trait to be passed
down from one
generation to the next
Section Three: Theory of Natural
Selection
 Natural selection
 A process by which
individuals that have
inherited beneficial
adaptations produce more
offspring on average than
do other individuals


Observed in populations
Population: all the
individual of the same
species that live in the same
area
 Thomas Malthus added
that availability of
resources also had an effect
on species survival
Section Three: Theory of Natural
Selection
 Natural Selection
 Helps to explain how
evolution can occur

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Variation
Overproduction: having
many offspring raises the
chances of survival but also
increases competition
Adaptation
Descent with modificaton:
descending from the same
organism but with some
changes
Fitness: the measure of the
ability of an organism to
survive and reproduce
Section Three: Theory of Natural
Selection
 Natural Selection
 Acts on existing
variation


If an organism’s
environment changes,
natural selection will
cause a change in the
organisms
Adaptations do not make
an individual perfectly
suited for its environment
Section Four: Evidence of Evolution
 Evidence for Evolution
 Fossils
 Geography


Migration of individuals
from mainland to islands
Biogeography: the study of
the distribution of
organisms around the world
 Embryology
 Embryos of different kinds
of animals can sometimes
be hard to tell apart
 Adds to the idea of common
descent
Section Four: Evidence of Evolution
 Evidence for Evolution
 Anatomy

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
Homolgous Structures
 Features that are similar in structure but appear in different
organisms and have different functions
 Ex: forelimbs of certain animals
Analogous Structures
 Structures that perform similar functions
 Ex: bat wings and wings of a fly
Vestigial Structures
 Remnants of organs or structures that had a function in early
ancestors
 Ex. Pelvic and hind limb bones in snakes
Section Four: Evidence of Evolution
Section Five: Evolutionary Biology
Today
 Evolutionary Biology
 Paleontology: the study
of fossils or extinct
organisms
 DNA sequencing
 Pseudogenes: like
vestigial structures
 Homeobox genes:
control development of
specific structures
 Protein comparison