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http://upload.wikimedia.org/wikipedia/commons/4/44/Haeckel_Prosobranchia.jpg
As European civilization grew its people had the curiosity and
ambition to explore the edges of the Earth, and across vast
oceans and in distant lands they found amazing creatures at
once incredibly different to those at home, and yet remarkably
the same. There was no explanation for such magnificent
diversity and enduring similarity until one man, visiting distant
isles, had an incredible revelation . . .
http://www.ronscobie-marineartist.com/Brierholme%20oval.JPG
Evolution:
The process by
which species
and populations
change over time
Decent with
modification . . .
http://www.cambridgeshire.gov.uk/NR/rdonlyres/F3840F96-432F-4D02-ADED4C791BBBC29E/0/Darwin.jpg
Darwin and Natural Selection
• Variation exists within species
• Organisms produce more offspring than
the environment can provide for
• Competition exists among individuals
• Organisms whose variations best fit the
environment will survive, reproduce, and
pass on their advantageous variations to
their offspring
Pojeta, John Jr. and Dale A.
Springer 2001
http://upload.wikimedia.org/wikipedia/commons/thumb/7/70/Phylogenetic_tree.svg/800px-Phylogenetic_tree.svg.png
Evidence has Been Found in Many
Places:
•
•
•
•
Geology and the Fossil Record
Biogeography
Developmental Biology
Molecular Biology
Fossils
provide the
dimension of
time in the
story of
evolution
http://www.gutenberg.org/files/20417/20417-h/images/image158.jpg
Principle of Superposition
Sedimentary rock layers are formed sand grain
by sand grain, gravel bit be gravel bit, until a
new layer of rock is formed, new layers form
on top of older layers, and so the youngest
layers are always at the top of a rock formation
and the oldest at the bottom.
Interesting to know: Steno was one of
the first to recognize fossils when in
1667 recognized the similarity of
“tongue stones” to sharks teeth
http://www.ucmp.berkeley.edu/history/s
teno.html
Ayala, Francisco J et al., 2008
http://photography.nationalgeographic.com/staticfiles/NGS/Shared/StaticFiles/Photography/Images/POD/s/staircase-escalante-building-522011-xl.jpg
Radioisotope Dating
• When radioactivity was discovered, so was a way to
measure the age of rocks
• Rocks are made of atoms, some are undergoing
radioactive decay
• This means they emit particles and energy at a
measurable constant rate
• Measurements can be taken to see how many atoms
have decayed, which provides insight into how old the
rock is
• This is called the natural clock of geology
http://science.howstuffworks.com/carbon-14.htm/ and
http://sps.k12.mo.us/jms/cartoon.htm and
http://www.ipj.gov.pl/en/szkolenia/glossaryEN.htm
http://media-2.web.britannica.com/eb-media/90/790-004-A1844BBC.gif
http://www.nzetc.org/tm/scholarly/Bio10Tuat02-fig-Bio10Tuat02_P001a.html
Law of Fossil Succession
• Fossils are the remains of once living
organisms
• The vast majority of fossils are the
remains of the hard parts of extinct
organisms
• The types of fossils found differ because
life on Earth has changed
•Fossils are the primary
evidence for how species
evolved over time
•Hundreds of thousands of
fossils show succession of
forms over time
•Including fish to
amphibian
•Amphibian to reptile and
reptile to mammal
•Importantly, fossils give
consistent evidence of
systematic change over
time without any reversals
(Ayala, Francisco J et al.
2001)
http://labspace.open.ac.uk/file.php/4128/S182_7_005i.jpg
Common Structures
Fossils can show homologies between species that show a
common ancestor (as can comparative anatomy)
Homologies are structures two or more species have in
common though they may not be used for the same purpose
http://www.nap.edu/openbook.php?record_id=6024&page=14 and http://upload.wikimedia.org/wikipedia/commons/6/64/Handskelett_MK1888.png
Whereas useless in this circumstance, these rudiments... have
not been eliminated, because Nature never works by rapid
jumps, and She always leaves vestiges of an organ, even
though it is completely superfluous, if that organ plays an
important role in the other species of the same family.
–Etienne Geoffroy Saint-Hilaire 1798
http://en.wikipedia.org/wiki/%C3%89tienne_Geoffroy_Saint-Hilaire
Developmental Biology
•Evolution is not perfectly efficient
•As new species evolve from old species
they often carry with them old traits
that no longer serve any purpose
•These traits are known as vestigial traits
and can by anatomical, biochemical or
behavioral in nature
•These traits are further evidence of an
ancestral relationship
Blind Mole Rat:
Can’t see a thing
with their eyes
covered by skin
flaps, but still
has eyes
Ostriches: still have
wings, but cannot fly
Coccyx: the tailbone of a
human, a vestigial
attribute from our tailed
ancestors
Whale: Note the bones labeled “c,”
they are the vestigial memory of
hind legs
http://en.wikipedia.org/wiki/Vestigial and
http://farm2.static.flickr.com/1166/1186161894_7f69d19604.jpg?v=0
Biogeography
Biogeography
• There is an enormous amount of diversity,
and yet many common forms and
migration’s influence on the development
of new species
• Explains the multiplicity of related species
in remote localities
• Explains the absence of many organisms
on islands and multiplicity of a few kinds
Phylogenetic Tree of Galapagos finches
http://porpax.bio.miami.edu/~cmallery/150/unity/c1x17b-finches.jpg
Finches in Context of Migration from
Mainland to Island
http://www.doe.mass.edu/mcas/student/2007/question.asp?GradeID=100&Subj
ectCode=bio_hs&QuestionTypeName=&QuestionID=5357
Molecular Biology
• Provides the mechanism of
evolution
• Provides evidence of a
common ancestor
• Provides additional
information about when
speciation occurs and
history of relationships
between species by
examining the molecular
clock and pseudogenes
http://www.ch.cam.ac.uk/magnus/molecules/nucleic/
dna1.jpg
Mechanism for Evolution
• In the year following Darwin, all of this evidence accumulated
in favor of evolution, yet until the discovery of modern
genetics, the mechanism for variation was not known
• Greg Mendel first noted patterns in heredity, however with
Watson and Crick’s discovery of the double helix we have
now come so far as to understand chromosomes, genes and
DNA
• DNA is the ultimate source of variation, when sperm, eggs, or
daughter organisms are created, the DNA of the parent must
be replicated to provide the template of the organism
• When DNA replicates it is not a perfect process and small
errors will occur, most are corrected in the process, but some
are not, these are mutations
• Mutations provide the variation between individuals within a
species necessary for natural selection to occur
http://universe-review.ca/I11-33-mutations.jpg
A Common Basis
• All living things share the same
biochemical machinery from algae
to elephants
• Proteins are virtually identical from
fruit flies to mice to humans and all
life uses the same 20 amino acids
• All living things use the same
biochemical system to pass genetic
information from one generation to
another
• This adds enormous weight to the
idea of a common ancestor
http://www.ageds.iastate.edu/meat/images/dna2.gif
All living organisms share common structures for DNA, RNA, and the 20 amino
acids
http://www.talkorigins.org/faqs/molgen/
Molecular Clock
• Genes have been used to reconstruct the
evolutionary history of species
• Mutations occur constantly
• Genes evolve at different rates because
some genes are more tolerant to change
than others
• When geneticists consider this they can
create maps of when species may have
diverged
Pseudogenes and Phylogenetic Trees
• As species change some genes that were
once useful lose their functionality
• They are still passed on to offspring, but are
not expressed, just carried along like excess
baggage
• They are useful to determine past
relationships between species
• The degree of similarity of these genes
between different species reflects the degree
of relatedness as it is improbable they
evolved independently
Works Cited
Ayala, Francisco J et al. 2008. Science, Evolution, and Creationism. The
National Academies Press. National Academy of Science and Institute of
Medicine. Washington D.C.
Bowler, Peter J. 2003. Evolution: The History of an Idea. University of California
Press. Berkley
Gardner, Robert. 2005. Genetics and Evolution Science Fair Projects. Enslow
Publishers. Berkeley Heights. 123-124
Krukonis, Greg and Tracy Barr. 2008. Evolution for Dummies. Wiley Publishing,
Inc.
Larson, Edward J. 2004. Evolution: The Remarkable History of a Scientific
Theory. The Modern Library. New York
Hilaire, Geoffroy.1798. "Observations sur l'aile de l'Autruche, par le citoyen
Geoffroy", La Decade Egyptienne, Journal Litteraire et D'Economie Politique
1 (pp. 46–51). Embedded in <
http://en.wikipedia.org/wiki/Vestigial#cite_note-3>
Pojeta, John Jr. and Dale A. Springer. 2001. Evolution and the Fossil Record.
American Geological Insitute. Alexandria, Virginia <agiweb.org>
Taylor, Paul D. 2000. Eyewitness Books: Fossil. Dorling Kindersley. London