1. Evolution and Biodiversity
Chapter 4

2. Key Concepts Origins of life Evolution and evolutionary processes
Ecological niches
Species formation
Species extinction

3. How Did We Become Such a Powerful Species So Quickly?
Strong opposable thumbs
Walk upright
Intelligence
Fig. 4-1, p. 63

4. Origin & Evolution of Life
Chemical evolution - 1st billion yrs organic molecules, biopolymers & chemical rxns needed for formation of first cells (Age of Earth = 4.6 billion years)
Biological evolution - first life 3.7 bya (prokaryotes) “Populations - not individuals - evolve by becoming genetically different.”

5. Animation- Chemical Evolution
Stanley Miller's experiment animation

6. Biological Evolution of Life
Modern humans
(Homo sapiens)
appear about
2 seconds
before midnight
Recorded human
history begins
1/4 second
before midnight
Origin of life
(3.6–3.8 billion
years ago)
Fig. 4-3, p. 66

7. How Do We Know Which Organisms Lived in the Past?
Fossil record
Radiometric dating
Ice cores
DNA studies
Fig. 4-2, p. 65

8. Biological Evolution
Evolution= change in populations genetic makeup over time (“Populations - not individuals - evolve by becoming genetically different.”)
“Theory” of evolution= All species descended from earlier, ancestral species
Microevolution= small genetic changes in a population
Macroevolution= long-term, large scale evolutionary changes (speciation, extinction)

9. Natural Selection
Definition: Process where particular beneficial trait is reproduced in succeeding generations more than other traits
Three Conditions: 1. Genetic Variability 2. Trait must be inherited (selection occurs) 3. Differential Reproduction - individuals w/ trait have more offspring

10. Adaptations Structural- coloration, mimicry, protective, gripping
Physiological - hibernate, chemical
Behavioral - ability to fly, migrate

11. Animation
Change in moth population animation
“Genes mutate, individuals are selected, and populations evolve.”

12. Animation
Adaptive trait interaction

13. Ecological Niches and Adaptation
Ecological niche = occupation (role)
Habitats = address
Fundamental niche = no competition
Realized niche = with competition

14. Specialized Feeding Niches for Birds
Herring gull is a
tireless scavenger
Brown pelican dives for fish,
which it locates from the air
Black skimmer
seizes small fish
at water surface
Ruddy turnstone searches
under shells and pebbles for small invertebrates
Avocet sweeps bill through
mud and surface water in
search of small crustaceans,
insects, and seeds
Dowitcher probes deeply
into mud in search of
snails, marine worms,
and small crustaceans
Scaup and other
diving ducks feed on
mollusks, crustaceans,
and aquatic vegetation
Flamingo
feeds on
minute
organisms
in mud
Knot (a sandpiper) picks up
worms and small crustaceans
left by receding tide
Oystercatcher feeds on
clams, mussels, and
other shellfish into which
it pries its narrow beak
Piping plover feeds
on insects and tiny
crustaceans on
sandy beaches
Louisiana heron wades into
water to seize small fish
Fig. 4-5, p

15. Broad and Narrow Niches and Limits of Adaptation
Generalist species - broad niche
Specialist species - narrow niche, more extinction-prone under changing environmental conditions. Which is better?
Limits of adaptation- gene pool & reproductive capacity
Refer to Spotlight, p. 69- cockroaches

16. Niches of Specialist and Generalist Species
Specialist species
with a narrow niche
Generalist species
with a broad niche
Niche
separation
Number of individuals
Niche
breadth
Region of
niche overlap
End Pt 1
Resource use
Fig. 4-4, p. 68

17. Stabilizing selection animation.

18. Disruptive selection animation.

19. Evolutionary Divergence of Honeycreepers
Unknown finch ancestor
Fruit and seed eaters
Insect and nectar eaters
Greater Koa-finch
Kona Grosbeak
Akiapolaau
Maui Parrotbill
Kuai Akialaoa
Crested Honeycreeper
Apapane
Amakihi
Fig. 4-6, p. 70

20. Misconceptions of Evolution
“Survival of the fittest” OK if: Fitness = reproductive success ≠ strongest
“Progress to perfection”

21. Speciation What is speciation? Geographic isolation
Reproduction isolation mutation & natural selection operate independently in gene pools of geographically isolated populations original populations become genetically distinct- unable to produce live, fertile offspring

22. Geographic Isolation can Lead to Speciation
Arctic Fox
Adapted to cold through heavier fur, short ears, short legs, short nose. White fur matches snow for camouflage.
Northern
population
Spreads northward
and southward
and separates
Early fox
population
Different environmental
conditions lead to different
selective pressures and evolution
into two different species.
Gray Fox
Adapted to heat through lightweight fur and long ears, legs, and nose, which give off more heat.
Southern
population
Fig. 4-7, p. 71

23. Animation
Speciation on archipelago animation

24. Extinctions Background extinctions= 1-5 species per million
Mass extinctions- five previous mass extinctions: 25% - 75% species go
Mass depletions- > background, but < mass
Human impacts - 6th major mass extinction???

25. Mass Extinctions of the Earth’s Past
Fig. 4-9, p. 73

26. Factors Leading to Extinction
Plate tectonics
Climatic changes over time-most
Natural catastrophes
Human impacts

27. “Continental Drift” (Plate Tectonics): The Breakup of Pangaea
GONDWANALAND
LAURASIA
NORTH AMERICA
ANTARTICA
AUSTRALIA
AFRICA
EURASIA
SOUTH AMERICA
INDIA
MADA
GASCAR
225 million years ago
135 million years ago
65 million years ago
Present
Fig. 4-8, p. 72

28. Changes in Biodiversity over Geologic Time
1600
Terrestrial organisms
Silurian
Devonian
Permian
Triassic
Jurassic
1200
Cambrian
Ordovician
Cretaceous
Pre-cambrain
Carboniferous
Marine organisms
Number of families
800
Tertiary
Quaternary
400
3500
545
500
440
410
355
290
250
205
145 65
1.8
Millions of years ago
Fig. 4-10, p. 74

29. Future of Evolution Artificial selection (selective breeding)
Genetic engineering (gene splicing)
Genetic modified organisms (GMOs)
Cloning
Ethical concerns

30. Genetically Engineered Mouse
Mouse on right has human growth hormone gene- grows 3x faster and 2x larger
Fig. 4-12, p. 76

31. Genetic Engineering Links
Genetic Engineering and Society, Lecture 1a, Honors Collegium 70A, UCLA
Watch This Lecture. Take Notes and turn in for 10 activity points
Yale University online Lectures- Genetic Engineering
Alternative to UCLA lecture.
Future of genetic engineering - by Futurist Dr Patrick Dixon.