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…)

7

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…

8

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…

9

Voyage of the Beagle

10

SeasicknessDarwin got VERY seasick.

Spent 3 of the 5 years on land

11

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

13

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

14

Species have high reproductive potential

Produce WAY more offspring than can possibly survive

Why?

15

Consider the elephant

16

Life is hard…

17

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…

19

Glyptodonts & ArmadillosIn Argentina, Darwin observed fossils of extinct glyptodonts

Animals resembledliving armadillos

20

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

21

VariationDarwin observed variation in all living species

22

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

25

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.

26

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.

27

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

32

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…

37

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

49

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!

54