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Lecture #13 Week #11
A.K. Morris, Ph.D.
Ocean Life & EvolutionChapter 12
1
Great moments in evolution
Evolution“THE” foundation for understanding life
ecologicalbehavioralphysiologicalmolecular
Deviating a bitfrom the book…
2
DNAThe blue print for all life
All living organisms have the same parts, just different combinations
We’re all related at some level
Let’s take a brief trip in history…
3
CHARLES DARWIN (1809–1882)
• Born same day as Abraham Lincoln
• Sent to medical school, but dropped out
• Childhood fascination with nature
• Only way to study nature was in the clergy.
4
19th Century - New Theories
Scholars attempt to reconcile evidence of change w/ creationism
Cuvier - multiple catastrophes
Lamark - inheritance of acquired characteristics
5
Sir Charles Lyell (1797-1875)
Remember him???
“Uniformitarianism” proponent(Earth formed by slow continuous processes)
Promoted “Geologic Time”
Wrote “Principles of Geology”(12 editions! 1830-1875)
Focus on processExplained fossils on mountaintops
Challenged the view that Earth is 6,000 years old
6
Lecture #13 Week #11
A.K. Morris, Ph.D.
Inside cover of “Principles of Geology”(way before it’s time…)
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Captain Robert FitzRoy (1805-1865)
Brilliant young sea captain
A science enthusiast
Read “Principles of Geology”, and actually knew Lyell
Assigned captain of the HMS Beagle after the previous captain shot himself
Didn’t want to be lonely on his next voyage, so…
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The Connection…
• Approached Darwin (FitzRoy’s second choice)
• FitzRoy gave Darwin a copy of Lyell’s book – he was fascinated by it.
• He had observed barnacles on cliff tops and now had potential explanation
• Armed with this new paradigm, he took a little trip with FitzRoy…
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Voyage of the Beagle
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SeasicknessDarwin got VERY seasick.
Spent 3 of the 5 years on land
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Spent much time on horseback in S. America.(avoiding the boat)
Collected specimens and made careful observations.
12
Lecture #13 Week #11
A.K. Morris, Ph.D.
Darwin’s Big Idea
• After the Beagle cruise, Darwin never set foot on a boat EVER again.
• Amassed a huge amount of data.
• Spent years analyzing it all
• Began formulating ground breaking ideas
• But he was scared of the implications
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Malthus - Struggle to SurviveThomas Malthus (1766-1834), well known economist contemporary of Darwin
Argued that as pop size increases, resources dwindle, the struggle to live intensifies and conflict increases
Influenced Darwin – provided aframe of reference for hisdeveloping ideas
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Species have high reproductive potential
Produce WAY more offspring than can possibly survive
Why?
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Consider the elephant
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Life is hard…
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Many survive. Many survive.
But not
all…
18
Lecture #13 Week #11
A.K. Morris, Ph.D.
The challenge:Environment:
Cold, hot, windy, wet, dry, etc…
Food: Not enough, not right kind, not right time…
Predators:One or many…
Competition:Too slow, too weak, too scared, too dumb…
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Glyptodonts & ArmadillosIn Argentina, Darwin observed fossils of extinct glyptodonts
Animals resembledliving armadillos
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Galapagos Islands
Off coast of Ecuador
Observed unique spp. but similar to mainland
Hypothesis: Descended from spp that arrived from elsewhere
Isabela
Darwin
Wolf
Pinta
Marchena Genovesa
Fernandia
SantiagoBartolomé
RabidaPinzon
SeymourBaltraSanta Cruz
Santa FeTortuga
Española
San Cristobal
Floreana
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VariationDarwin observed variation in all living species
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Variation in length of adult humerus bonesin an extinct bird (La Brea Tar Pits)
23© A.K. Morris
Variability exists in all living organisms
Darwin saw this
Individuals with different traitsEx. Lighter vs. darker, taller vs. shorter
Some traits convey an advantage…
Reflect/absorb sun keeps them cooler/warmer
24
Lecture #13 Week #11
A.K. Morris, Ph.D.
Darwin’s Big Idea
Species differ in traits that are heritable
Affects ability to survive and reproduce
B/c spp produce more offspring than resources, spp will compete
Causes populationsto change over time
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Natural SelectionNatural Selection - Differential survival and reproduction of indiv. in a pop.
Over time, filtering, along w/ changing environment causes changes in genetic makeup/ traits in populations
Take Home Message:Evolution is a continuousprocess…Natural Selection is themechanism.
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Organisms w/ favorable traits survive better and reproduce more
Traits get passed to next generation
I’m da man…
Ladies, one at a time, please.
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Selection (continued)Selection (continued)Indiv. w/ unfavorable traits do not Indiv. w/ unfavorable traits do not survive survive or or reproducereproduce. .
Only genes for Only genes for favorablefavorable traits are passedtraits are passed
Darwin award winnerDarwin award winner28
Think of nature like a filter. Environment:-climate-predators-habitat-disease-etc.
Future generations
29
Natural SelectionHow it works:
Darwins 4 simple steps
1. Organisms reproduce more than can survive
2. All populations have variation
3. Some variation is heritable
4. Over time, as the environment changes, a population will end up exhibiting more favorable traits (e.g. frequency of favorable alleles increases)
30
Lecture #13 Week #11
A.K. Morris, Ph.D.
Alfred WallaceArrived at same conclusions as Darwin
Wrote to Darwin describing his views
Prompted Darwin to finally present his ideas in a formal paper
Darwin waited 20 years – knew it would be controversial
They presented it together in 1858 (sort of… Darwin didn’t show up) – didn’t get much fanfare.
But…31
Origin of SpeciesPublished in 1859
Sold out in the first day
Not immediately accepted
By 1930s, science had maturedPopulation EcologyGeneticsGame TheorySystematics
Natural Selection provided a mechanism that connected allof these disciplines
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Artificial SelectionFor thousands of years, humans have been modifying species by “artificial selection”
But not everyone was convinced that such a thing could happen on a large time scale
The smoking gun eludedDarwin
33
Early Ideas About Heredity Everyone knew that sperm & eggstransmitted info from parents
Blending inheritance???
Totally stumped Darwin
Problem:Expect variation to disappear
And yet variation persists…
34
?
Father Gregor MendelCzech mathematicianLOVED gardening
Published in 1865, and rediscovered in 1900
His work described behavior of chromosomes (where genes reside) during cellular reproduction (aka meiosis)
Never knew DNA existed…
35
How much change can happen over long periods of time?
36
Lecture #13 Week #11
A.K. Morris, Ph.D.
Adaptation…Changes in morphology, physiology, or behavior that help organisms cope w/ environment
Natural selection produces indiv’s adapted to survive in a particular environment…
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DiversityLife is diverse because species adapt in different ways
But they maintain some similarities because they possess the same basic traits from common ancestors
38
Evolution today
The modern synthesis
Marries Darwin’s initial concept with genetics and population theory.
Major debates in science around Evolution were basically over by the end of the 1920s.
What factors “force” rapid evolutionary changes?
39
Mass Extinctions
Fig. 12.2 40
Box 13.1, p. 36841 42
Lecture #13 Week #11
A.K. Morris, Ph.D.
Box 13.1, p. 368
Chicxulub Crater, Yucatán Mexico
43
Evidence for EvolutionMore evidence exists for evolution than for the Theory of Gravity
FossilBiogeographyAnatomicalBiochemicaland many others…
44
Fossil EvidenceEvery fossil is one more line of evidence…
Simplest Complex thru geological time
Archaeopteryx
45 46
Anatomical EvidenceVestigial structures (advantageous at one time)
Humans: tail bone, appendix, body hair, etc.
Others: hind limbs in whales and snakes
47
Anatomical EvidenceHomology versus Analogy
YOU!
48
Homologous structures
Lecture #13 Week #11
A.K. Morris, Ph.D.
Anatomical EvidenceAnalogous structures
All these animals have evolved flat swimming structures independently
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Biochemical EvidenceWhether you are a crab, an amoeba, giant kelp, or a blue whale, we all follow these same rules:
This NEVER varies
DNA = A-C-T-G, RNA = A-C-U-G
Genetic Code is Universal
20 amino acids to build EVERYTHING
50
Small genetic abnormalities give us glimpses of our past?
How many nipples do you have?
51"A Remarkable Case of External Hind Limbs In A Humpback Whale" By Roy Chapman Andrews. American Museum of Natural History, Novitates No. 9. 1921 52
TOKYO, Japan (AP) – “Japanese researchers said Sunday that a bottlenose dolphin captured last month has an extra set of fins that could be the remains
of hind legs, a discovery that may provide further evidence that ocean-dwelling mammals once lived on land”.
November 5, 2006
www.cnn.com/2006/TECH/science/11/05/japan.dolphins.ap/index.html
53
So, all living populations evolveBut there are other unifying things…
All living things are made of CELLS
We all METABOLIZE
We all REPRODUCE
…to be continued next week!
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