This document summarizes key concepts about evolution and biodiversity including the origins of life through chemical evolution, the development of early prokaryotes, and subsequent biological evolution. It describes evolutionary processes like natural selection, adaptations, speciation, mass extinctions, and factors influencing extinction. Timelines show major events in the evolution of life on Earth and changes in biodiversity over geologic time.

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

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. Fig. 4-3, p. 66
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)
Biological Evolution of Life

7. How Do We Know Which
Organisms Lived in the Past?
 Fossil record
 Radiometric dating
 Ice cores
 DNA studies

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

12. Adaptive trait interaction
Animation

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

14. 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. 72- cockroaches

15. Niche
separation
Specialist species
with a narrow niche
Generalist species
with a broad niche
Niche
breadth
Region of
niche overlap
Niches of Specialist and
Generalist Species
Resource use
Number
of
individuals

16. Animation
Stabilizing selection animation.

17. Animation
Disruptive selection animation.

18. Specialized Feeding Niches for
Birds
Black skimmer
seizes small fish
at water surface
Flamingo
feeds on
minute
organisms
in mud
Scaup and other
diving ducks feed on
mollusks, crustaceans,
and aquatic vegetation
Brown pelican dives for fish,
which it locates from the air
Avocet sweeps bill through
mud and surface water in
search of small crustaceans,
insects, and seeds
Louisiana heron wades into
water to seize small fish
Oystercatcher feeds on
clams, mussels, and
other shellfish into which
it pries its narrow beak
Dowitcher probes deeply
into mud in search of
snails, marine worms,
and small crustaceans
Knot (a sandpiper) picks up
worms and small crustaceans
left by receding tide
Herring gull is a
tireless scavenger
Ruddy turnstone
searches
under shells and
pebbles for small
invertebrates
Piping plover feeds
on insects and tiny
crustaceans on
sandy beaches
Fig. 4-10, p. 72

19. Cockroaches: Nature’s Ultimate
Survivors
Fig. 4-11, p. 72

20. 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
Evolutionary Divergence of
Honeycreepers

21. Misconceptions of Evolution
 “Survival of the fittest”
Fitness = reproductive success ≠ strongest
 “Progress to perfection”

22. 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

23. Fig. 4-8, p. 68
Spreads northward
and southward
and separates
Arctic Fox
Gray Fox
Adapted to cold
through heavier
fur, short ears,
short legs, short
nose. White fur
matches snow
for camouflage.
Adapted to heat
through
lightweight fur
and long ears,
legs, and nose,
which give off
more heat.
Different environmental
conditions lead to different
selective pressures and evolution
into two different species.
Northern
population
Southern
population
Early fox
population
Geographic Isolation can Lead to
Speciation

24. Speciation on archipelago animation
Animation

25. Factors Leading to Extinction
 Plate tectonics
 Climatic changes over time
 Natural catastrophes
 Human impacts

26. 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???

27. LAURASIA
AFRICA
EURASIA
225 million years ago 135 million years ago
65 million years ago Present
Fig. 4-6, p. 66
“Continental Drift” (Plate Tectonics): The
Breakup of Pangaea

28. Mass Extinctions of the Earth’s Past

29. Terrestrial
organisms
Marine
organisms
Quaternary
Tertiary
Cretaceous
Jurassic
Triassic
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
Pre-cambrain
1.8 0
65
145
205
250
290
355
410
440
500
545
3500
0
1600
1200
800
400
Number
of
families
Millions of years ago
Changes in Biodiversity over
Geologic Time

30. Fig. 4-B, p. 69
Genetically Engineered Mouse
Mouse on right has
human growth
hormone gene-
grows 3x faster and
2x larger