Transcript 15.2 Evidence of Evolution

Chapter 15.1/2 Notes Pg. 84
Section 1: Darwin’s Theory of Natural Selection
Section 2: Evidence of Evolution
E.Q. - Identify and explain
how the evidences of
evolution can be used
To show common ancestry.
Chapter 15
Evolution
Darwin on the HMS Beagle
 Darwin was hired as naturalist
 His job was to collect biological and geological
specimens during the ship’s travel.
 Populations from the mainland changed after
reaching the Galápagos.
Chapter 15
Evolution
15.1 Darwin’s Theory of Natural Selection
The Galápagos Islands
 Darwin began to collect finches and other
animals on the four islands.
 He noticed that the different
islands seemed to have
their own, slightly different
varieties of animals.
Chapter 15
Evolution
15.1 Darwin’s Theory of Natural Selection
Darwin Continued His Studies
 Darwin hypothesized that new species could
appear gradually through small changes in
ancestral species.
Chapter 15
Evolution
Darwin proposes Natural Selection
 A process by which organisms with
favorable variations reproduce at higher
rates than those without such variations.
• In simple terms
“ survival of the fittest”
Chapter 15
Evolution
15.1 Darwin’s Theory of Natural Selection
The Origin of Species
 Darwin published On the
Origin of Species by Means
of Natural Selection in
1859.
6 Evidences of Evolution
1.Fossil Record (biogeography)
2.Vestigial Structures
3.Homologous Structures
4.Analogous Structures
5.Embryology
6.Comparative Biochemistry*
*also called macromolecules
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Evolution
15.2 Evidence of Evolution
 The fossil record
 Fossils provide a record of species that lived long ago.
 Fossils show that ancient species share similarities
with species that now live on Earth.
Glyptodont
Armadillo
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15.2 Evidence of Evolution
Vestigial Structures
 Structures that are in an
organism that serve no
known function.
ex=appendix of humans
 Vestigial structures might
have been used by
ancestors.
Hind limb of a whale
15.2 Evidence of Evolution
 Anatomically similar structures inherited
from a common ancestor are called
homologous structures.
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Evolution
15.2 Evidence of Evolution
 Analogous structures can be
used for the same purpose
and can be superficially similar
in construction, but are not
inherited from a
common ancestor.
ex: wings
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Evolution
15.2 Evidence of Evolution
Comparative Embryology
 Vertebrate embryos
exhibit homologous
structures during
certain phases of
development but
become totally different
structures in the adult
forms.
Chapter 15
Evolution
15.2 Evidence of Evolution
Comparative Biochemistry (macromolecules)
Amino acids are used
to show similarities.
Similar species =
similar amino acid
sequences
Chapter 15
Evolution
Derived vs. Ancestral traits
 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
and tails, that do appear in
ancestral forms.
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15.2 Evidence of Evolution
Types of Adaptation
 An adaptation is a trait that
increases an organism’s
reproductive success.
(a trait that helps it survive)
Webbed feet = adaptation
 Fitness is a measure of the relative
contribution an individual trait makes to the
next generation.
(how well does it survive/reproduce)
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Evolution
15.2 Evidence of Evolution
Camouflage
 Allows organisms to
become almost
invisible to predators
Leafy sea dragon
Orchid Praying Mantis
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15.2 Evidence of Evolution
Mimicry
 One species evolves to resemble another
species.
Western coral snake
California kingsnake
Notes REView ?’s
Answer each with clear explanations.
1. What islands did Darwin stop at? What did
he see? What idea did he propose?
2. Explain natural selection in your own
words. (provide example)
3. List/describe all six different types of
evidence used to show common ancestry.
** explain each and provide example of each
4. Explain what an adaptation is and give two
human adaptations as examples.