Download evidence for evolution

EVIDENCE
FOR
EVOLUTION
(SECTION 8.2)
Darwin’s Observations
• Page 329
THE VOYAGE
• Collected thousands
of specimens.
• Collected fossils that
resembled existing
animals.
• Volcanic Galapagos
Islands had species
similar to S. American
mainland species.
• Species differed from
island to island.
DARWIN’S FINCHES
• Collected on
Galapagos.
• Beaks modified to suit
food source (niche).
• Descended from
common mainland
ancestor.
• Different species
found on separate
islands.
Adaptive Radiation
of Galapagos Finches
• New species branched out from older
ones to fill available ecological niches
Darwin’s
Conclusion
• All life on earth is related
• Currently existing
organisms are
descendants of past
organisms
• The mechanism for
evolution is natural
selection.
Fossils
• Shows numbers of
extinct animals
• Shows similarities
between extinct animals
and animals that are
alive today
• The earth’s layers show
a time scale of species
and when they
appeared on earth (and
when they died out)
How Fossils Form
• http://www.youtube.com/watch?v=TVwPL
WOo9TE
Transitional Fossils
(Missing Links)
• Archaeopteryx
– link between
dinosaurs & birds
– Lived 150 million
years ago
– Discovered 1861,
just two years
after Darwin
published Origin
of Species
Whale Evolution
• Video
http://www.y
outube.com/
watch?v=I2
C-3PjNGok
Tiktaalik
• Transition
from water
to land
• http://www.y
outube.com/
watch?v=o5
Z4mPQBjqA
• Darwinius
masillae (“Ida”)
is the
approximately
47-million-yearold common
ancestor of
anthropoid
primates: that
is, all monkeys
and apes,
including
humans
Ida
Biogeography
• Homologous structures – these are parts of the
body that are similar, but have different functions
 The flippers of
whales, and the
wings of birds
 All forelimbs of
vertebrates have the
same pattern of
bones
 Common ancestry
Divergent evolution
Homologous Structures
Analogous Structures
– Some species of
different origins have
similar physical
structures (convergent
evolution)
– Example1: the wings of
bats and insects
– Example 2: the eyes of
vertebrates, molluscs
(like squid and octopus)
and insects
Evidence of Divergent &
Convergent Evolution
HOMOLOGOUS
ANALOGOUS
• Vestigial Organs – these are organs or parts that
seem to have no function in the living organism,
but once had a function in an ancestor
Whales have pelvic bones that do not attach to
legs
Remember Lamarck’s theory of disuse?
Embryological Development
Embryos of different species develop in almost identical
ways.
Human fetus at 8 weeks
Biochemistry and DNA
When comparing the DNA sequence of a gene or amino acid
sequence of a protein between two species, more similarities
are found in species that are more closely related.
Lion photo credit: ucumari Tiger photo credit: digitalART2
Comparing DNA or Amino Acid
Sequences
http://darwiniana.org/intro1.htm
Cytochrome C oxidase
(mitochondrial protein found in all eukaryotes)
http://www.citruscollege.edu/lc/archive/biology/Pages/Chapter17-Rabitoy.aspx
Cladogram
(Phylogenetic Tree)
http://evolution.berkeley.edu/evolibrary/article/0_0_0/endosymbiosis_05
Primate
Evolution
Direct observation of species change
1. Bacteria become resistant to antibiotics
2. Artificial Selection
A. Plants and animals were “domesticated” for
agriculture
B. Wolves were bred over many generations to
become dogs and then bred further to create
a variety of breeds
Another example of Artificial Selection
Pests become resistant to chemicals.
What Evolution is NOT
The theory of evolution is an explanation
of the diversity and distribution of life
forms on earth.
It is not an explanation of the initial
origin of life.
This is an active area of research called
“abiogenesis,” “astrobiology,” or simply
origin of life (OOL).
It is obviously part of the larger scientific
project to understand the universe, but is
• Creationism, sometimes referred to as “creation
science” or “intelligent design” is the belief that
organisms were placed on this earth by a divine
being (God).
• It is NOT a scientific theory because it does not
follow scientific principles
• Scientific theories require evidence, and must
be based on NATURAL PHENOMENON
• Finding gaps in our knowledge about evolution is
a normal part of the scientific process, the
existence of these “gaps” and questions does not
qualify as evidence that an alternative theory
must be correct
• Many religious organizations do not have a
problem with evolution, and it is compatible with
their faith and beliefs.
• Ask your religious leaders what their thoughts
are.
Also see the National Centre for Science Education
for a list of statements from a variety of religious
groups.
Here’s an excellent lecture by Kenneth Miller
http://media.hhmi.org/hl/06Miller.html
HOMEWORK
•
•
•
•
•
Read Sections 7.1, 7.2 & 8.2
Page 304 #1-9
Page 311 # 2, 7, 8, 11
Page 340 # 6, 7, 10 – 13, 15 – 17
HIV evolution video
– http://www.youtube.com/watch?v=34GeUa7R
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