biol 102 chp 25 history of life
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This is a lecture presentation for my BIOL 102 General Biology II students on Chapter 25: History of Life (Biology 9E by Campbell et al, 2011). Rob Swatski, Assistant Professor of Biology, Harrisburg Area Community College - York Campus, York, PA. Email: [email protected] Please visit my website, BioGeekiWiki, for more biology learning resources: http://robswatskibiology.wetpaint.com Visit my Flickr photostream for anatomy model photographs! http://www.flickr.com/photos/rswatski/ Thanks for looking!TRANSCRIPT
The History of The History of Life on EarthLife on Earth
BIOL BIOL 102: 102: General Biology IIGeneral Biology II
Chapter Chapter 2525
Rob Rob SwatskiSwatski Assoc. Prof. BiologyAssoc. Prof. Biology
HACCHACC--YorkYork 1
MacroMacro--evolutionevolution
Changes over large time scales are observed in the fossil record
Emergence of terrestrial
vertebrates
Origin of flight in birds
Long-term impacts of mass
extinctions 2
The First The First CellsCells
1. Abiotic synthesis of small organic
molecules
2. Bonding small molecules into
macromolecules
3. Packaging macromolecules into protocells
4. Origin of self-replicating molecules
3
Synthesis of Synthesis of Organic Organic
CompoundsCompounds
Earth formed 4.6 BYA, along with
rest of solar system
The early atmosphere
contained water vapor & …
… chemicals released by
volcanic eruptions
N2, NOx, CO2, CH4, NH3, H2, H2S
4
AbioticAbiotic Synthesis Synthesis HypothesesHypotheses
Oparin & Haldane (1920’s)
Early atmosphere was a reducing
environment
Miller & Urey
(1953)
Abiotic synthesis of organic molecules in a
reducing atmosphere is possible
5
Ma
ss
of
am
ino
ac
ids
(m
g)
Nu
mb
er
of
am
ino
ac
ids
20
10
0
1953 2008
200
100
0
1953 2008
Amino acid synthesis in a simulated volcanic eruption – 2008 reanalysis of Miller study
7
Alternative Alternative AbioticAbiotic Synthesis HypothesesSynthesis Hypotheses
1st organic molecules may
have been synthesized near
volcanoes & deep-sea hydrothermal
vents
Meteorites seeded the Earth with
amino acids
Small organic molecules polymerize
when concentrated on hot sand, clay, or rock
11
AbioticAbiotic Synthesis of Synthesis of MacromoleculesMacromolecules
• RNA monomers have been produced spontaneously from simple molecules
• Small organic molecules polymerize when they are concentrated on hot sand, clay, or rock
12
ProtocellsProtocells
Replication & metabolism are key
properties of life & may have appeared together
Protocells may have been fluid-
filled vesicles enclosed by a
membrane-like structure
Display simple replication & metabolism
Also maintain an internal chemical
environment 13
ProtocellProtocell EvidenceEvidence
Protocells can be easily made in the
lab; adding clay increases their
formation
Form spontaneously from abiotically
produced organic molecules
Small membrane-bound droplets
(liposomes) form when lipids are added
to water
Display simple metabolism
14
Time (minutes)
Precursor molecules plus
montmorillonite clay
Precursor
molecules only
Rela
tiv
e t
urb
idit
y,
an
in
de
x o
f ve
sic
le n
um
ber
0 20 40 60 0
0.2
0.4
Vesicle selfVesicle self--assembly in assembly in montmorillonitemontmorillonite clayclay 15
Phosphate
Maltose
Phosphatase
Maltose
Amylase
Starch
Glucose-phosphate
Glucose-phosphate
Simple Metabolic PathwaySimple Metabolic Pathway 18
RNA & SelfRNA & Self--ReplicationReplication
The 1st genetic material was
probably RNA, not DNA
Special RNA molecules
(ribozymes) can catalyze many
different reactions
Ribozymes can make complementary copies of short
stretches of RNA
20
The “RNA The “RNA World”World”
Early protobionts with self-
replicating, catalytic RNA …
… would have been more effective at
using resources & …
… would have increased in number via natural selection
RNA could have provided a
template for the more stable DNA
22
Evidence Evidence from the from the
Fossil RecordFossil Record Fossils reveal changes in
the history of life on Earth
Sedimentary rocks are deposited into layers
(strata) & are the richest source of fossils
Few individuals have fossilized & even fewer have been discovered
The fossil record is biased in favor of species that: existed for a long time,
were abundant, widespread, & had hard
parts 27
Dimetrodon
Stromatolites
Fossilized stromatolite
Coccosteus cuspidatus
4.5 cm
0.5 m
2.5
cm
Present
Rhomaleosaurus victor
Tiktaalik
Hallucigenia
Dickinsonia costata
Tappania
1 cm
1 m
100 mya
175
200
300
375 400
500 525
565
600
1,500
3,500
270
29
RhomaleosaurusRhomaleosaurus victor, victor, a plesiosaur (200a plesiosaur (200--65.5 65.5 myamya))
30
DimetrodonDimetrodon,, a large a large carnivorouscarnivorous synapsidsynapsid
more closely related to more closely related to mammals than reptiles mammals than reptiles
(270 (270 myamya))
32
2.5 cm EdiacaranEdiacaran (565 (565 myamya) ) –– softsoft--bodied invertsbodied inverts 41
DickinsoniaDickinsonia costatacostata
How Rocks How Rocks & Fossils & Fossils
Are DatedAre Dated Sedimentary strata reveal the relative
ages of fossils
The absolute ages of fossils are determined by
radiometric (radiocarbon) dating
A “parent” isotope decays to a
“daughter” isotope at a constant rate
Each isotope has a known half-life, the
time required for half the parent
isotope to decay 47
Time (halfTime (half--lives)lives)
Accumulating “daughter” isotope
Remaining “parent” isotope
1 2 3 4
1/2
1/4
1/8
1/16
48
The Origin of The Origin of MammalsMammals
Mammals belong to the tetrapod group
Mammalian evolution can be traced using
anatomical evidence
The common ancestor of mammals & reptiles are the synapsids (300
mya)
The most recent common mammalian
ancestors are the therapsids (280 mya) 49
OTHER
TETRAPODS †Dimetrodon
†Very late (non-
mammalian)
cynodonts
Mammals
Syn
ap
sid
s
Th
era
psid
s
Cyn
od
on
ts
Reptiles
(including
dinosaurs and birds)
Temporal
fenestra
Hinge
Temporal
fenestra
Hinge
Synapsid (300 mya)
Therapsid (280 mya)
Key to skull bones
Articular
Quadrate
Squamosal
Dentary
Hinge
Hinge
Hinges
Temporal
fenestra
(partial view)
Early cynodont (260 mya)
Very late cynodont (195 mya)
Later cynodont (220 mya)
Key to skull bones
Articular
Quadrate
Squamosal
Dentary
Origin of solar
system and
Earth
Prokaryotes
Atmospheric oxygen
Archaean
4
3
Proterozoic
2
Animals
Multicellular
eukaryotes
Single-celled
eukaryotes
Colonization
of land
Humans
Cenozoic
1
The First The First Unicellular Unicellular OrganismsOrganisms
The oldest known fossils are
stromatolites (3.5 bya)
Rock-like structures composed of many layers of bacterial mats & sediment
Prokaryotes were the Earth’s only
inhabitants from 3.5 to 2.1 BYA
Microfossils 56
The First The First PhotosynthesisPhotosynthesis
Most atmospheric oxygen (O2) is of biological origin
Bacteria similar to modern cyanobacteria
were the likely O2 source
O2 produced by photosynthesis reacted
with dissolved iron
Precipitated to form banded iron
formations 2.7 bya 61
The Oxygen The Oxygen RevolutionRevolution
Lasted from 2.7 to 2.3 BYA
Oxidation posed a challenge for life &
caused the extinction of many prokaryotic
groups
But, it provided an opportunity to gain energy from light
Allowed organisms to exploit new ecosystems
64
“Oxygen “Oxygen
revolution”revolution”
Time (billions of years ago)
4 3 2 1 0
1,000
100
10
1
0.1
0.01
0.0001
Atm
os
ph
eri
c O
2
(perc
en
t o
f p
resen
t-d
ay levels
; lo
g s
cale
)
0.001
65
The First The First EukaryotesEukaryotes
The oldest eukaryotic cell fossils are 2.1 BYA
old
Endosymbiosis
Mitochondria & plastids (chloroplasts & related organelles)
were once prokaryotes living inside larger host
cells
Endosymbiont: a cell living within a host
cell 66
EndosymbiontEndosymbiont TheoryTheory
Prokaryotic ancestors of mitochondria & plastids probably entered host
cells as undigested prey or internal parasites
As they became more interdependent, the host & endosymbionts became a
single organism
Serial endosymbiosis: mitochondria evolved
before plastids through a series of endosymbiotic
events
Membrane invagination 67
Nucleus
Cytoplasm
DNA
Plasma membrane
Endoplasmic reticulum
Nuclear envelope
AncestralAncestral prokaryoteprokaryote
Serial Serial EndosymbiosisEndosymbiosis
68
Infolding of plasma membrane
Aerobic heterotrophic prokaryote
Mitochondrion
Ancestral heterotrophic Ancestral heterotrophic eukaryoteeukaryote
69
Ancestral photosynthetic Ancestral photosynthetic eukaryoteeukaryote
Photosynthetic prokaryote
Mitochondrion
Plastid
70
Key Evidence Key Evidence Supporting Supporting
EndosymbiosisEndosymbiosis Mitochondria & plastids
have similar inner membrane structures & functions as prokaryotes
Their division is similar to some prokaryotes
They can transcribe & translate their own DNA
Their ribosomes are more like prokaryotic ribosomes
71
The Origin of The Origin of MulticellularityMulticellularity
Eukaryotic cell evolution allowed for more diverse
unicellular forms
A 2nd wave of diversification occurred when multicellularity
evolved
Gave rise to algae, plants, fungi, & animals
Comparisons of DNA sequences date the
common ancestor of multicellular eukaryotes to
1.5 bya 72
Oldest known Oldest known multicellularmulticellular eukaryote fossils eukaryote fossils –– Algae (1.2 BYA)Algae (1.2 BYA)
73
150 µm TwoTwo--Cell StageCell Stage
Fossilized Fossilized Animal Animal
EmbryoEmbryo (575 MYA)(575 MYA)
74
“Snowball “Snowball Earth” Earth”
HypothesisHypothesis
Periods of extreme polar glaciation
Life confined to the equatorial region …
… or deep-sea vents
750 to 580 MYA
77
EdiacaranEdiacaran Biota Biota
Evolution of larger organisms
More diverse forms of life
Wide variety of soft-bodied animals
575 to 535 MYA
78
The The Cambrian Cambrian ExplosionExplosion
The sudden appearance of fossils resembling
modern phyla in a relatively short time
period
Huge increase in biodiversity: soft-bodied, shelled, &
segmented animals
First evidence of predator-prey interactions
Cambrian period: 535 to 525 MYA
79 SanctacarisSanctacaris
Sponges
Cnidarians
Echinoderms
Chordates
Brachiopods
Annelids
Molluscs
Arthropods
Ediacaran Cambrian
PROTEROZOIC PALEOZOIC
Time (millions of years ago)
635 605 575 545 515 485 0
81
• DNA analyses suggest that many animal phyla diverged before the Cambrian explosion, perhaps as early as 700 million to 1 BYA
• Fossils in China provide evidence of modern animal phyla tens of millions of years before the Cambrian explosion
• The Chinese fossils suggest that “the Cambrian explosion had a long fuse”
The The Colonization Colonization
of Landof Land Fungi, plants, & animals began to colonize land
around 500 MYA
Fungi & plants likely colonized land together
by 420 MYA
Arthropods & tetrapods are the most
widespread & diverse land animals
Tetrapods evolved from lobe-finned fishes around 365 MYA
83
85
What are the challenges to a What are the challenges to a terrestrial lifestyle?terrestrial lifestyle?
Factors Influencing the Factors Influencing the Rise & Fall of Rise & Fall of BiodiversityBiodiversity
Continental drift
Mass extinctions
Adaptive radiations
86
Continental Continental DriftDrift
Earth’s continents move slowly over the
underlying hot mantle
Oceanic & continental plates
Plates collide, separate, or slide past each other
Interactions result in the creation of mountains, islands, & earthquakes
87
Mantle
Crust
Outer
core
Inner
core
Juan de Fuca
Plate
North
American
Plate
Caribbean
Plate
Cocos Plate
Pacific
Plate Nazca
Plate
South
American
Plate
Eurasian Plate
Philippine
Plate
Indian
Plate
African
Plate
Antarctic
Plate
Australian
Plate
Scotia Plate
Arabian
Plate
88
Mill
ion
s o
f ye
ars
ago
Mill
ion
s o
f ye
ars
ago
135
Me
sozo
icM
eso
zoic
251
Pal
eo
zoic
Pal
eo
zoic
History ofHistory of Continental DriftContinental Drift
91
South America
Mill
ion
s o
f ye
ars
ago
Mill
ion
s o
f ye
ars
ago
65.5
Eurasia
India
Africa
Antarctica
Madagascar
Ce
no
zoic
Ce
no
zoic
Present
92
Effects of the Pangaea Effects of the Pangaea SuperSuper--ContinentContinent
(250 (250 myamya))
A reduction in shallow
water habitat
A colder & drier inland
climate
Climate change as continents
moved toward &
away from the poles
Changes in ocean
circulation patterns
leading to global
cooling 93
Biological Biological Impact of Impact of Pangaea Pangaea BreakBreak--UpUp
Allopatric speciation
Led to the current distribution of plants,
animals, & fossils
Ex: similarity of fossils in areas of South America & Africa
Re-shaped biodiversity via booms & busts
94 CynognathusCynognathus
Mass Mass ExtinctionsExtinctions
The fossil record reveals that most species that have ever lived are now
extinct
At times, the extinction rate
increased dramatically
Resulted in 5 mass extinctions
Over 50% of Earth’s species became extinct in each
event 96
Tota
l ext
inct
ion
rat
eTo
tal e
xtin
ctio
n r
ate
(f
amili
es
pe
r m
illio
n y
ear
s):
Time (millions of years ago)Time (millions of years ago)
Nu
mb
er
of
fam
ilie
s:
Nu
mb
er
of
fam
ilie
s:
CenozoicCenozoic MesozoicMesozoic PaleozoicPaleozoic E O S D C P Tr J
542
0
488 444 416 359 299 251 200 145
Era Period
5
C P N
65.5
0
0
200
100
300
400
500
600
700
800
15
10
20
98
Mass Extinction & the Diversity of LifeMass Extinction & the Diversity of Life
Permian Permian Mass Mass
ExtinctionExtinction Between Paleozoic & Mesozoic eras (250
MYA)
Occurred in < 5 MY
Led to largest mass extinction: 95% of all
marine species & 70% of terrestrial
species
May have been caused by volcanism,
leading to climate change & reduced
oceanic O2 100
101
El Capitan Permian ReefEl Capitan Permian Reef --Guadalupe MountainsGuadalupe Mountains National Park, TXNational Park, TX
Cretaceous Cretaceous Mass Mass
ExtinctionExtinction Between Mesozoic &
Cenozoic eras (65 MYA)
50% of all marine species became
extinct, along with …
… many terrestrial plants & animals,
including most dinosaurs
The presence of iridium in
sedimentary rocks suggests a meteorite
impact 102
106
The Sixth The Sixth Mass Mass
ExtinctionExtinction
The current extinction rate is 100-1000X the
normal background rate
Extinction rates tend to increase when
global temperatures increase
Data suggest that a 6th human-caused
Holocene mass extinction is
currently underway
Mass extinctions
Cooler Warmer
Re
lati
ve
ex
tin
cti
on
ra
te o
f m
ari
ne
an
ima
l g
en
era
3
2
1
0
1
2 3 2 1 0 1 2 3 4
Relative temperature
Fossil Extinctions & TemperatureFossil Extinctions & Temperature
107
Consequences Consequences of Mass of Mass
ExtinctionExtinction
Alters ecological communities & available niches
It can take 5-100 MY for diversity to
recover
Creates potential for adaptive radiations
108
Pre
dat
or
gen
era
Pre
dat
or
gen
era
(p
erc
en
tage
of
mar
ine
ge
ne
ra(p
erc
en
tage
of
mar
ine
ge
ne
ra)
Time (millions of years ago)Time (millions of years ago)
CenozoicCenozoic MesozoicMesozoic PaleozoicPaleozoic E O S D C P Tr J
542
0
488 444 416 359 299 251 200 145
Era Period C P N
65.5 0
10
20
30
40
50
109
Mass Extinctions & EcologyMass Extinctions & Ecology
Adaptive Adaptive Radiation of Radiation of
MammalsMammals
Underwent an adaptive radiation after the extinction
of terrestrial dinosaurs
Allowed increase in diversity & size of
mammals
Why?
110
CynodontCynodont
Millions of years agoMillions of years ago
Monotremes (5 sp)
250 150 100 200 50
ANCESTRAL CYNODONT
0
Marsupials (324 sp)
Eutherians (placental mammals; 5,010 sp)
Ancestral mammal
111
Adaptive Radiation of MammalsAdaptive Radiation of Mammals
Other Examples of Other Examples of Adaptive RadiationsAdaptive Radiations
Photosynthetic prokaryotes
Land plants Large Cambrian
predators Insects & tetrapods
112
Close N. Amer. relative, the tarweed Carlquistia muirii
Argyroxiphium sandwicense
Dubautia linearis Dubautia scabra
Dubautia waialealae
Dubautia laxa
HAWAII 0.4 MY
OAHU 3.7 MY
KAUAI 5.1 MY
1.3 MY
MOLOKAI MAUI
LANAI
113 Regional ARegional Adaptivedaptive Radiation on the Hawaiian IslandsRadiation on the Hawaiian Islands
Evolutionary Evolutionary Effects of Effects of
Developmental Developmental GenesGenes
Developmental genes control the …
… rate, timing, & spatial pattern of
development
Major changes in body form can result
Studying genetic mechanisms of change
can provide insight into large-scale
evolutionary change 114
Chimpanzee fetus
Chimpanzee adult
Human fetus Human adult
HeterochronyHeterochrony
An evolutionary change in the rate or
timing of developmental events
Can have a significant impact on body shape
Differential growth rates
The contrasting shapes of human &
chimpanzee skulls are due to small changes
in relative growth rates 116
PaedoPaedo--morphosismorphosis
The rate of reproductive development accelerates
compared with somatic
development
The sexually mature species may retain body features that
were juvenile structures in an
ancestral species
Ex: salamanders
117
Changes in Changes in Spatial Spatial PatternPattern Evolutionary change
is also due to alterations in genes
controlling the placement &
organization of body parts
Homeotic genes: determine basic
features including:
Location of wing & leg development on a bird
The arrangement of a flower’s parts
119
HoxHox GenesGenes
A class of homeotic genes providing
positional info during development
If Hox genes are expressed in the wrong location, body parts can
be produced in the wrong location
In crustaceans, a swimming appendage
can be produced instead of a feeding appendage
Evolution of vertebrates from invertebrates was
associated with two alterations in Hox genes
120
HoxHox gene expression & limb developmentgene expression & limb development
Limbless regions
Snake embryo Chicken embryo
121
Changes in Changes in GenesGenes
New morphological forms likely come
from gene duplication events that produce new
developmental genes
The evolution of 6-legged insects from a
many-legged crustacean ancestor
has been demonstrated in lab
experiments
Specific changes in the Ubx gene can “turn
off” leg development
Ex: Drosophila & Artemia 122
Hox gene 6 Hox gene 7 Hox gene 8
About 400 mya
Drosophila Artemia
Ubx
123 Origin of the insect body planOrigin of the insect body plan
Changes in Changes in Gene Gene
RegulationRegulation
Changes in body form may be caused by changes in
how developmental genes are regulated instead of
changes in their sequence
Ex: three-spine sticklebacks in lakes have fewer ventral spines than their marine
relatives
The gene sequence stays the same, but the regulation of gene
expression is different in the two groups of fish
124
Marine stickleback embryo
Close-up of ventral surface (spines)
Lake stickleback embryo
Close-up of mouth
No spines
125
Loss of spines in lake stickleback fish: change in the Loss of spines in lake stickleback fish: change in the regulation of regulation of Pitx1Pitx1 gene expressiongene expression
Evolution is Evolution is Not GoalNot Goal--OrientedOriented
Natural selection can only improve a
structure in the context of its current use
New forms arise through the slight
modification of existing forms
Most novel biological structures evolve in many stages from previously existing
structures
Complex eyes evolved independently from
simple photosensitive cells many times 126
(a) Patch of pigmented cells
Optic nerve Pigmented
layer (retina)
Pigmented cells (photoreceptors)
Fluid-filled cavity
Epithelium
Epithelium
(c) Pinhole camera-type eye
Optic nerve
Cornea
Retina
Lens
(e) Complex camera lens-type eye
(d) Eye with primitive lens Optic nerve
Cornea Cellular mass (lens)
(b) Eyecup
Pigmented cells
Nerve fibers Nerve fibers
127
128
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