Transcript Evolution Notes


Hypothesis An “If…then” statement or
proposal of an outcome of an experiment.
› (Ex. If I study, then I will pass the test.)

Theory A hypothesis that has withstood
extensive testing by a variety of methods, and
a higher degree of certainty may be placed
› (Ex. Theory of Evolution)

Law Considered universal & invariable
facts of the physical world
› (Ex. Law of Gravity)


Main idea: Multiple lines of evidence support the theory of
evolution.
Objectives:
› Describe how fossils provide evidence of evolution.
› Discuss morphological evidence of evolution.
› Explain how physiology and biochemistry provide evidence of
evolution.
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Review Vocabulary:
› Fossil – remains of an organism or its activities

New Vocabulary
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Derived trait
Ancestral trait
Homologous structure
Vestigial structure
Analogous structure
Embryo
Biogeography
Fitness
Mimicry
Camouflage
Chapter
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Evolution
15.2 Evidence of Evolution
Support for Evolution
 The fossil record
 Provide a record of species that lived long ago.
 Show that ancient species share similarities
with species that now live.
Glyptodont
Armadillo
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The giant armadillo-like
glyptodont,
Glyptodon,is an
extinct animal that
Darwin thought must
be related to the living
armadillos that inhabit
South America,
Central America, and
the southern United
States.
The fossil record is an
important source of
information for
determining the
Chapter
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Evolution
15.2 Evidence of Evolution
Support for Evolution
 Geographic Distribution
 The distribution of plants and animals that
Darwin saw first suggested evolution to
Darwin.
Mara
Rabbit
Chapter
15
Evolution
15.2 Evidence of Evolution
 Derived traits are newly evolved
features, such as feathers, that do not
appear in the fossils of common
ancestors.
Ancestral traits are more primitive
features, such as teeth & tails, that
do appear in ancestral forms.
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Anatomically
similar structures
inherited from a
common ancestor
are called
homologous
structures.
The forelimbs of
vertebrates are
adapted for
different uses, but
they all have
similar bones.
Similar structure;
different function.
 Anatomically
similar structures inherited
from a common ancestor
Analogous structures can
be used for the same
purpose and can be
superficially similar in
construction, but are not
inherited from a common
ancestor.
 Show that functionally
similar features can evolve
independently in similar
environments.
 Same function; different
structure
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Chapter
15
Evolution
Analogous Structures
 Same function but different
structure
 NOT inherited from
common ancestor.
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Vestigial structures are
the reduced forms of
functional structures in
other organisms.
Evolutionary theory
predicts that features
of ancestors that no
longer have a function
for that species will
become smaller over
time until they are lost.
Examples: Snake pelvis
and human appendix.
Chapter
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Evolution
15.2 Evidence of Evolution
Vestigial Structures
 Structures that are the
reduced forms of functional
structures in other organisms.
 Evolutionary theory
Says features of ancestors that no
longer have a function will become smaller over
time until they are lost.
Chapter
15
Evolution
15.2 Evidence of Evolution
 Comparisons of the similarities in organisms
are seen in comparative anatomy and in the
fossil record.
 Organisms with closely related
morphological features have more closely
related molecular features.
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An embryo is an
early pre-birth
stage of an
organism’s
development.
Vertebrate
embryos exhibit
homologous
structures during
certain phases of
development
but become
totally different
structures in the
adult forms.


embryo- it’s the earliest stage of development
reptiles, birds, and mammals all have similarities
 tail, organs, eye placement etc…

Common
ancestry
can be seen
in the
complex
metabolic
molecules
that many
different
organisms
share.
Comparisons of the similarities in these
molecules across species reflect
evolutionary patterns seen in
comparative anatomy and in the fossil
record.
 Organisms with closely related
morphological features have more
closely related molecular features.
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The distribution of plants and animals that
Darwin saw first suggested evolution to
Darwin.
Rabbit
Mara

The distribution of plants and animals that
Darwin saw first suggested evolution to
Darwin.
Rabbit
Mara
 Fitness –
ability of an individual to
survive and reproduce in a specific
environment
 Adaptation – inherited characteristic
that increases an organism’s chance
of survival
› Can be physical traits as well as
behavioral traits

Types of Adaptation
› An adaptation is a trait shaped by natural
selection that increases an organism’s
reproductive success.
› Fitness is a measure of the relative contribution
an individual trait makes to the next generation.
It is often measured as the number of
reproductively viable offspring that an organism
produces in the next generation.
› Camouflage allows organisms to become
almost invisible to predators. Some species have
evolved morphological adaptations that allow
them to blend in with their environments.
› Mimicry is another morphological adaptation
that allows one species to evolve to resemble
another species.
Antimicrobial
resistance - An
antibiotic is a
medicine that slows
or kills the growth of
bacteria.
 Some bacteria
have evolved a
resistance to
certain antibiotics.
 People infected
with resistant
bacteria can never
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Some features of an organism might be
consequences of other evolved
characteristics.
 They do not increase reproductive
success.
 Features likely arose as an unavoidable
consequence of prior evolutionary
change.

-behaviors that increase fitness
For ex: aggression in bee’s
Chapter
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Evolution
15.2 Evidence of Evolution
Camouflage
 Allows organisms to
become almost
invisible to predators
Leafy sea dragon
Camouflage- blend in with surroundings
Camouflage- blend in with surroundings
Chapter
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Evolution
15.2 Evidence of Evolution
Mimicry
 One species evolves to resemble another
species.
Western coral snake
California kingsnake