Transcript Notes ppt. over the evidence of evolution

Photo by “davemee” flickr
creative commons
"nothing in biology makes sense
except in the light of evolution”
~Theodosius Dobzhansky (1900Evolution of Hip Hop Dances
1975)
http://youtu.be/ZTpn30Pms8I
How are humans speeding up
Evolution?
• https://www.youtube.com/watch?v=LzlUZrt0Um
s&feature=youtube_gdata_player
• Why do so many different animals
have the same structures, the arm
bones in a human are the same
bones as a flipper in a whale?
• Why is the sequence of DNA very similar
in some groups of organisms but not in
others?
• Why do the embryos of animals look very
similar at an early stage?
Photo courtesy of Swamibu, Flickr Creative Commons
Marine Iguana, photo courtesy of mtchm, flickr
creative commons
Blue-footed booby, photo courtesy of stirwise,
flickr creative commons
Finch, photo courtesy of stirwise, flickr,
creative commons
Giant tortoise, photo courtesy of Planetgordon,
flickr creative commons
• Darwin noted that there
existed many finches on
the islands, but while they
had similarities, each was
adapted to eating a
particular type of island
food
• He concluded that the
finches all came from one
ancestral species and
evolved into many new
species
Cactus finch, photo courtesy of zrim,
flickr creative commons
• Darwin published this
work to explain the
variety of species
that exist on the
planet
• He proposed the
“Theory of Evolution
by Natural Selection”
• Natural selection
provided a mechanism for
evolutionary change in
populations.
Evidence supporting evolution
• Fossil record
– shows change over time
• Anatomical record
– comparing body structures
• homology & vestigial structures
• embryology & development
• Molecular record
– comparing protein & DNA sequences
• Biogeography
Fossil Evidence
• Shows numbers 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)
Dinosaurs have always fascinated us, movies such as
Jurassic Park capitalize on that fascination.
How do we know what dinosaurs
looked like?
We create a picture based on the
bones we find (fossils) and use
modern reptiles to guess at their
texture and skin color.
1. Fossil record
• Layers of rock contain fossils
– new layers cover older ones
• creates a record over time
– fossils show a series of organisms have lived on
Earth
• over a long period of time
Fossils tell a story…
Primate Fossils
Australopithecus
sapien
Homo erectus
Homo
Relative vs.
Absolute
Dating
Fossil
2. Anatomical record
Animals with different
structures on the surface
But when you look under
the skin…
It tells an evolutionary story
of common ancestors
Ex: Homologous structures
• Structures that come from the same origin
• homo- = same
• -logous = information
• Forelimbs of human, cats, whales, & bats
– same structure
• on the inside
– different functions
• on the outside
– evidence of common ancestor
ex. The flippers of whales, and the wings of
birds
All forelimbs of vertebrates have the same
pattern of bones
• Common ancestry
But don’t be fooled by these…side note
 Analogous
structures
 look
similar on the outside
 same function
 But different
How is a bird
 structure & development on the inside
like a bug?
 different origin
 no evolutionary relationship
Solving a similar problem with a similar solution
In your notes….
• In one sentence, write your answer to the following
question…..
– What is the difference between homologous and
analogous structures?
• 2nd side note: Vestigial Organs – these are
organs or parts that seem to have no function
Why would whales have
pelvis & leg bones if they
were always sea creatures?
Because they
used to
walk on land!
Ex: Embryological Development
Embryos of different species develop in almost identical
ways.
Human fetus at 8 weeks
3. Molecular record
• Comparing DNA & protein structure
– everyone uses the same genetic code!
• DNA
 compare
common genes
 compare
common
proteins
number of amino acids
different from human
hemoglobin
Human
Macaque
Dog Bird
Frog
Lamprey
8
32 45
67
125
0 10 20 30 40 50 60 70 80 90 100 110 120
• Biochemistry and DNA continued
When comparing the DNA of one species to another, more
similarities are found in species that are more closely
related.
Lion photo credit: ucumari Tiger photo credit: digitalART2
DNA
4. Biogeography
Biogeography focuses on the study of how life forms are
distributed over the geographical areas of the earth
giving evidence to the theory of evolution. It provides
knowledge of distribution through geological time on
both species and the ecosystem. Speculation, glaciation,
extinction and continual drift all provide explanations of
how species spread and locate to various geographical
locations through ecosystem energy exchanges.
Convergent Evolution
These animals have evolved similar adaptations
for obtaining food because they occupy similar
niches. What can you infer about their
phylogeny from their geographic locations?
Punctuated Equilibrium
“instead of a slow, continuous movement,
evolution tends to be characterized by long
periods of virtual standstill ("equilibrium"),
"punctuated" by episodes of very fast
development of new forms”
The "punctuated equilibrium" theory of Niles
Eldredge and Stephen Jay Gould was
proposed as a criticism of the traditional
Darwinian theory of evolution…what is it
called?
Convergent Evolution
• Species exposed to the
same selective pressure in
different parts of the world
tend to develop the same
adaptations
• Even though they may be
completely unrelated
• e.g. the placental wolf and
the marsupial thylacine or
Tasmanian wolf
© 2008 Paul Billiet ODWS
Thylacine Thylacinus cynocephalus
Wolf Canis lupus
Convergent evolution led to mimicry
• Why do these pairs look so similar?
Monarch male = poisonous
fly
bee
Viceroy male = edible
moth
bee
Divergent Evolution
• Populations of a species that are separated and
evolve under different selective pressures
develop different adaptations as they diverge
• They are usually geographically separated so that
there is a barrier to the mixing of genes
© 2008 Paul Billiet ODWS
Direct observation of species change
1.Bacteria become resistant to antibiotics
2.Wolves were bred over many generations to
become dogs (artificial selection) • and then bred
further to create a variety of breeds
3. Micro Evolution: Natural selection
in action: the evolution of
insecticide-resistance
•New insecticides are effective, killing 99% of the insects.
• The few survivors resist the chemical attack.
• Only these resistant individuals reproduce, passing on their
resistance.
• In each generation the percentage of insecticide-resistant
individuals increases.
• In general, natural selection operates not to create
variation, but to edit existing variation.
Fig. 22.12
• For patients treated with the drug 3TC, which
interferes with genome replication in HIV, 3TCresistant strains become 100% of the population of
HIV in just a few weeks.
Fig. 22.13
Endosymbiotic Theory