Transcript Evolution Notes

EVOLUTION 101
Darwin developed his revolutionary
proposal over time, influenced by the
work of others and by his travels.
March 2, 2016
Agenda:
- Power Words
- Biotechnology FRQ
- Darwin’s Ideas Notes
Charles Darwin Section 1 and 2
• An English naturalist
• 5 year voyage on the HMS
Beagle
• Galapagos Islands
• Journal: Observations,
questions, and discoveries
• Published “Origin of the
Species” 1859
Darwin travels the world
Unity and
Diversity of Life
Darwin’s Ideas
1. Descent with modification: Living and extinct animals
descended by reproduction from pre-existing species.
2. Theory of Natural Selection
1. Overproduction: Organisms have more offspring than
will survive to adulthood
2. Genetic variation: There are variations among
populations
3. Struggle for Survival: Individuals compete for
resources; some win, some lose. Some variations
(adaptations) improve their chances.
4. Differential reproduction: Well adapted survive,
reproduce, & pass on the traits that helped them win
(Survival of the fittest) After MUCH time, the population
contains mostly favorable traits
Galapagos Finches
Example of “descent with modification”
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13 Different species on the islands
Specific beak shape and size
Correlated with food source on island
Suspected they diverged from a
smaller group of ancestors
Overproduction
Overproduction and Genetic Variation
What determines survival?
Adaptations.
– Need traits that will help them survive
• predators
• disease
• competition for food
• competition for territory
– Traits that help individuals reproduce
• so they can attract a mate
• compete for nesting sites
• successfully raise young
– New species arise from gradual accummulation of
adaptations over long period of time in response to
changing environment.
Acclimatization (To acclimate)
A short-term process in which physiological
changes take place in a single being in its own
lifetime.
Example: An animal
adjusting to a new climate
by growing thicker fur.
Small changes over long
periods of time, multiple
generations.
Adaptation
Survival & Reproduction of the Fittest Bug…
Why does evolution matter now?
1.
Drug Resistant Pathogens
1. HIV: Resistant to Drug 3TC
2. Multi-Drug Resistant TB
3. DDT Resistant Mosquitoes
4. MRSA: Resistant Staph bacteria
2. Natural Selection = Edits and Selects,
It does not Create
Natural Selection vs. Artificial Selection
Artificial Selection
Domesticating wolves
15,000 years ago
Dog breeders
Choose specific animals
with specific traits to
reproduce.
Only heritable
traits, not
acquired traits
are passed to
offspring.
Key Misconceptions:
Individuals do not evolve.
The population does.
A favorable trait in one
environment may be
detrimental in another.
Evidence of Natural Selection and
Evolution Section 3
• Direct Observation
• Paleontological
– Fossils
• Distribution of Fossils
• Transitional Species
– Biogeography
• Anatomical and Embryological
• Molecular
From fossils we can infer,
– Adjacent/Horizontal
Layering
• Different organisms lived at
different times.
– Radioactive Dating
– Half-lives
– Relate Age Dating
– When and where an
organism existed
– Species have existed in
gradual sequence over
time
The Smoking Gun: The Walking Whale
• Even though scientists could predict what early whales
should look like, they lacked the fossil evidence.
• The smoking gun came in 1994, when paleontologists
found the fossilized remains of Ambulocetus natans,
"swimming-walking whale.“
– Its forelimbs had fingers and small hooves but its hind
feet were enormous given its size.
• When it swam, it moved like an otter, pushing back with its
hind feet and undulating its spine and tail.
• Modern whales propel themselves through the water with
their tail flukes but Ambulocetus still had a whip-like tail
and had to use its legs to provide most of the propulsive
force needed to move through water.
Livescience.com
Fossil
skeleton
sequence of
whales.
Horse Fossils
Biogeography
• Darwin observed animals that
seemed closely related yet lived in
different environments.
• Pangaea/Continental Drift
Anatomical Evidence
• Homologous
• Analogous
• Vestigial
Anatomy and Embryology
• Similar bone structure.
– Homologous structures or
organs, inherited from
common ancestors – look
the same but might have
different function
Homologies: Embryological Evidence
Phylogeny or Cladogram:
Shows relatedness/ancestry
Phylogeny
Branch length indicates
time/evolutionary change
or both
Cladogram
A difference cause of resemblance
• Analogous structures, have
related functions but don’t look
the same.
– Example #1: Birds, bats and moths
have wings, but the underlying
structure is different.
• Convergent Evolution:
Independent evolution of similar
features with a different lineage
– Example #2: Marsupials vs.
Eutherians
Similar
features.
Different
Lineage.
Sometimes
different
Biogeography.
Anatomy
• Vestigial Structures: Seem to serve no
function but resemble structures with
function
• Psuedogenes p474
– Human tailbone
– Pelvic bone of modern whales
– Human Appendix
Questions
Molecular Evidence:
Which is closest to humans?
If humans and chimps have similar
DNA this must mean…
A. Humans and chimps share a common
ancestor
B. Humans evolved from chimps
C. Chimps evolved from humans
D. Convergent evolution led to DNA similarities
Comparing DNA Sequences – Which
two species are the most similar?
Homologous, Analogous or Vestigial Structure?
Least likely homology…
A.
B.
C.
D.
E.
Wings of bat and arms of human
Hemoglobin of baboon and that of gorilla
Mitochondria of plant and that of animal
Wings of bird and that of insect
Brain of cat and that of a dog