Evolution
and
Diversification
of
Life
Origin and Evolution of
Life
OCN 201 Science of the Sea
Biology Lecture 2
The Handfish
-BBC Blue Planet
Grieg Steward, Professor
Department of Oceanography
Plankton Ecology
National Academies Press
Phytoplankton
Bacteria
Viruses
When do you think life began?
A: > 3 billion years ago
B: about 6000 years ago
C: < 2000 years ago
D: around 1990
E: I’m still waiting
Evolution
Nothing in biology makes sense except in the
light of evolution - Theodisius Dobzhansky
I am a creationist and an evolutionist. Evolution is God's, or
Nature's method of creation. Creation is not an event that
happened in 4004 BC; it is a process that began some 10 billion
years ago and is still under way.
4
Basis of Evolution by Natural Selection
‣
Heritability of traits from parent to offspring
‣
Variability among offspring (mutations, recombination)
‣
Over-production of offspring
‣
Selection by the environment: More individuals with
favorable traits will survive and reproduce than those with
unfavorable traits
5
Evolution is not
“just a theory”
Incomplete Separations
donkey
horse
mule or hinny
Incomplete Separations
False Killer Whale
Pseudorca crassidens
Bottlenose Dolphin
Tursiops truncatus
Wolphin
Keikaimalu
Missing Links
Missing Links
Discovered
2006
Missing Links
Discovered 2008 (Matt Friedman)
Dogs have been partly artificially
selected for extreme differences in
morphology - but there is frequent
interbreeding among the various
types.
These whales have been naturally
selected with little to no
interbreeding, resulting in
speciation
Same Species
Different Species
When was the Theory of Evolution by
Natural Selection first publicly presented?
A: 1776
B: 1858
C: 1903
D: 1918
E: 1982
at the Linnean Society of London
Whose ideas were presented?
A: Charles Darwin
On the Origin of Species Charles Darwin
B: Alfred Russel Wallace
On The Tendency of Varieties to Depart
Indefinitely from the Original Type Alfred Russel Wallace
C: David Lee Roth
D: A &B
E: None of the above
The Old Five Kingdom View of Life
Multi-Cellular
Eukaryotes
Single-Cell
Eukaryotes
Increasing Complexity
with time
Fungi
Plants
Protists
Prokaryotes
Prokaryotes
Animals
Fossil vs Molecular Evidence
‣
Early work relied on fossils - focus on plants and animals
‣
The evolutionary history of microbes was unclear
‣
Molecular evidence generally confirmed fossil evidence,
and also revealed the deep history of the microbial world
16
The History of an Organism is Written
in its DNA
• But how do we
interpret it?
• Can use changes in
DNA sequence over
time as a “molecular
clock”
Sequence Comparisons
Diversity and evolutionary relationships
Seq. A
1 2 Seq. B
Seq. C
A
ATACGGTCAC..
ATTCGCTCAC..
ATGCGGTCAC..
A
Distance matrix can then
be used to build a
phylogenetic tree
A
C
B
B
2
C
1
B
C
2
1
Sequence Comparisons
Diversity and evolutionary relationships
Seq. A
1 2 Seq. B
2 Seq. C
A
ATACGGTCAC..
ATTCGCTCAC..
G
ATGCGGTCAC..
A
Distance matrix can then
be used to build a
phylogenetic tree
A
C
B
B
2
C
1
B
C
2
1
2
2
The Three Domains of Life
The Molecular View
Prokaryotes
Eukaryotes
Eukaryota
20
A Fundamental Division
‣
‣
Prokaryotes (no nucleus)
•
Bacteria
DNA
•
Archaea
DNA
Eukaryotes (with nucleus)
DNA
and other internal compartments
21
Serial Endosymbiosis Theory
The Origins of the Eukaryotic Cell Type
Plants
Lynn Margulis
Animals
22
Origins of Animals
Multicellular
Colonial
Unicellular
Origins of Plants
Multicellular
marine alga
Colonial
Unicellular
Eukaryote
terrestrial moss
Pick the Bacterium
A
D
C
B
E
Classification of Life
•
The vast diversity of life makes sense when considered
in the light of evolutionary history
•
The splitting of one species into two leads to a nested
hierarchy of characteristics that can be shown as a
branching tree
Hierarchical Classification
Linnean
Taxonomy
• Species
• Genus
• Family
• Order
• Class
• Phylum
• Kingdom
• Domain
Bottlenose
dolphin
Orca
Common
Octopus
delphis
orca
vulgaris
Delphinus
Orcinus
Octopus
Delphinidae
Delphinidae
Octopodidae
Cetacea
Cetacea
Octopoda
Mammalia
Mammalia
Cephalopoda
Chordata
Chordata
Mollusca
Animalia
Animalia
Animalia
Eukarya
Eukarya
Eukarya
Diversification of Life
CELL TYPE
DOMAIN
Prokaryotes
BACTERIA
ARCHAEA
Eukaryotes
EUKARYA
Animals
Plants
Photosynthesis
Phagotrophy
New mode of consumption
by engulfment
LUCA
?
Last Universal Common Ancestor
Microbial Fossils back to 3.5 bya
Fossil Stromatolites
Modern Stromatolites
29
50 million
190 million
500 million
Whales
Land mammals
Fish-like
700 million
ANIMALS
2 billion
Eukaryotes (Protists)
Photosynthesis
≥ 3.5 billion
Key Points
• Evolution is not uni-directional…but
• Simple things came first - complexity
accumulates slowly through trial and error via
many known mechanisms
• Eukaryotes arose through Serial Endosymbiosis
• The simple and the complex continue to co-exist
• As the earth changes, species die off and new
ones emerge