Bio 140. The Origin and Diversification of Life

1. Abiotic synthesis and accumulation of small organic molecules.

2. Joining of monomers into polymers.

3. Formation of protobionts.

4. Origin of heredity during or before protobiont appearance.

What are the Four stages of chemical evolution?

1. __________ synthesis and accumulation of small __________ molecules.

2. Joining of __________ into __________.

3. Formation of __________.

4. Origin of heredity during or before __________ appearance.

Oparin and J. B. S. Haldane (1920s)

They postulated that the reducing atmosphere and greater UV radiation enhanced reactions, joined simple molecules to produce the first organic molecules.

Stanley Miller and Harold Urey (1953)

They tested the Oparin-Haldane hypothesis in the lab using their famous experiment

Miller-Urey Experiment

This proved that simple organic molecules exist in space and can be produced by abiotic chemical reactions

Miller-Urey Experiment

apparatus with H₂O, H₂, CH₄ and NH₃ → organic molecules: amino acids, sugars, lipids, ATP, purines, pyrimidines

Protobionts

aggregates of abiotically produced molecules

Protobionts

exhibit some properties of life (metabolism; excitability; maintenance of an internal environment)

Coacervates

one type of protobiont formed when a suspension of macromolecules is shaken 

Coacervates

colloidal aggregates or droplets of polypeptides, nucleic acids, and polysaccharides that self assemble

Coacervates

These structures draw a lot of interest because they form spontaneously from aqueous mixtures and provide stable compartmentalization without the need of a membrane—they are protocell candidates.

RNA; DNA

Once the building blocks exist, the next crucial step is the origin of a simple replicating molecule

• which is ____ that eventually gave way to DNA

RNA

• first genetic material

• amino acids aligned along____ molecules by a primitive mechanism

• RNA; DNA

• proteins and enzymes evolved

• ______ chains base pair with each to produce ______

DNA replaced RNA as the genetic material because it is more stable

Why did DNA replace RNA as the main genetic material?

simpler than DNA

Pieces of evidence suggesting that RNA preceded DNA

Single-stranded RNA is ________________ which is always double-stranded.

ribozyme

Pieces of evidence suggesting that RNA preceded DNA

RNA can take on many different structures depending on its nucleotide sequence.

• some structural forms allow RNA to act as enzyme (or ___________), catalyzing biochemical reactions like replication of RNA

Uracil; Thymine

Pieces of evidence suggesting that RNA preceded DNA

“Pre-biotic soup” experiments (which simulate early Earth) have readily yielded the nucleotide _______ rather than ________

• possibly because RNA has a high mutation rate

  • This is because RNA is single stranded which makes it more exposed to mutagens.

• more complex life forms could not evolve until the mutation rate reduced

• the evolution of DNA would have led to a reduction of mutation rate

From an RNA world it became a DNA world.

Transition from RNA to DNA, what were the reasons why this happened?

• This is because RNA is single stranded which makes it more exposed to mutagens.

Why does RNA have such a high mutation rate?

• can capture energy from the environment

• can use that energy to replicate itself

• can carry out metabolism

Minimum criteria for a living cell:

• ________________________

• ________________________

• ________________________

• nucleic acids

• proteins

• lipid membrane

In living organisms, the said functions (minimum criteria for a living cell) are carried out by:

• __________ - carry information which can be replicated
  

• __________ - help replicate nucleic acids, transduced energy, and generate/constitute the phenotype
  

• ___________ - acts as a physical barrier that separates a cell's interior from its environment

  • It also serves as a structural and functional platform for many cellular processes, including signal transduction, cell recognition, and the transport of substances.

Archean

THE GEOLOGIC TIME SCALE

A. Pre-Cambrian Time

____________ (4-2.5 BYA): origin of life, diversification of prokaryotes, photosynthesis, aerobic respiration

Proterozoic

THE GEOLOGIC TIME SCALE

A. Pre-Cambrian Time

____________ (2.5 BYA-542 MYA): Earliest eukaryotes, cyanobacteria stromatolites, multicellularity, Cnidaria, Annelida, Arthropoda

Proterozoic

THE GEOLOGIC TIME SCALE

A. Pre-Cambrian Time

Mitochondria and Chloroplast descended from bacteria that were ingested and later became endosymbionts, in protoeukaryotes (earliest fossils: 1.5 BYA)

Proterozoic

THE GEOLOGIC TIME SCALE

A. Pre-Cambrian Time

Multicellularity probably evolved because of the advantage of “division of labor” between different cell types with different functions.

Proterozoic

THE GEOLOGIC TIME SCALE

A. Pre-Cambrian Time

Some Proterozoic fossils:

• Eontophysalis colony (cyanobacterium, 1.5 byo)

• Tappania (unicellular alga, 1.5 byo, N. Australia)

• Multicellular alga (590 myo)

Proterozoic

THE GEOLOGIC TIME SCALE

A. Pre-Cambrian Time

The Ediacaran Fauna of the late _________ and Early Cambrian were among the first animal fossils.

• They were flat, soft bodied creatures that crept or stood on the sea floor. Some members are Mawsonites spriggi (possibly Cnidarian) and wormlike Dickinsonia

The Ediacaran Fauna of the late Proterozoic and Early Cambrian

• They were flat, soft bodied creatures that crept or stood on the sea floor. Some members are Mawsonites spriggi (possibly Cnidarian) and wormlike Dickinsonia

Archean and Proterozoic

What were the eras under the A. Pre-Cambrian Time

Cambrian

THE GEOLOGIC TIME SCALE

B. Paleozoic era - which period?

___________ (542-488 MYA): Marine animals diversify, rapid emergence of most animal phyla and many classes (Cambrian explosion), diverse algae, earliest Agnathans;

Paleogene

Neogene

Quaternary

Cambrian

THE GEOLOGIC TIME SCALE

B. Paleozoic era - which period?

first evidence of predator-prey interactions; 488 MYA: series of extinction events

Paleogene

Neogene

Quaternary

Cambrian

THE GEOLOGIC TIME SCALE

B. Paleozoic era - which period?

most animals during this period lacked a skeleton, were small and soft so most did not fossilize.

• However, one of the few that did, was found in fossil beds in China which have yielded well-preserved remains of _____________ animals such as Jianfengia.

Paleogene

Neogene

Quaternary

Ordovician

THE GEOLOGIC TIME SCALE

B. Paleozoic era - which period?

______________ (488-444 MYA): Diversification of echinoderms, and agnathans (jawless fish); ended with mass extinction

Paleogene

Neogene

Quaternary

Silurian

THE GEOLOGIC TIME SCALE

B. Paleozoic era - which period?

__________ (439-416 MYA): Diversification of agnathans, origin of jawed fishes,

Paleogene

Neogene

Quaternary

Silurian

THE GEOLOGIC TIME SCALE

B. Paleozoic era - which period?

earliest terrestrial vascular plants, terrestrial arthropods

Paleogene

Neogene

Quaternary

Devonian

THE GEOLOGIC TIME SCALE

B. Paleozoic era - which period?

__________ (416-354 MYA): Diversification of bony fishes, trilobites, origin of ammonoids,

Paleogene

Neogene

Quaternary

Devonian

THE GEOLOGIC TIME SCALE

B. Paleozoic era - which period?

origin of amphibians, insects, ferns, seed plants.

Paleogene

Neogene

Quaternary

Carboniferous

THE GEOLOGIC TIME SCALE

B. Paleozoic era - which period?

______________ (359-299 MYA): Gondwana and smaller continents form, Extensive swamp forests of early vascular plants,

Paleogene

Neogene

Quaternary

Carboniferous

THE GEOLOGIC TIME SCALE

B. Paleozoic era - which period?

early orders of winged insect, diverse amphibians, first reptiles

Paleogene

Neogene

Quaternary

Permian

THE GEOLOGIC TIME SCALE

B. Paleozoic era - which period?

___________ (299-251 MYA): Continents approached and formed Pangea.

Paleogene

Neogene

Quaternary

Permian

THE GEOLOGIC TIME SCALE

B. Paleozoic era - which period?

Diverse order of insects, amphibians decline, reptiles include mammal-like forms, major mass extinctions at the end of the period.

Paleogene

Neogene

Quaternary

1. Cambrian (542-488 MYA)

2. Ordovician (488-444 MYA)

3. Silurian (439-416 MYA)

4. Devonian (416-354 MYA)

5. Carboniferous (359-299 MYA)

6. Permian (299-251 MYA)

From oldest to youngest, state each period of the Paleozoic era.

Mesozoic

C. ____________ era – “age of reptiles”

Triassic

THE GEOLOGIC TIME SCALE

C. Mesozoic era - which period?

____________ (251-200 MYA): Pangaea starts to break apart, gymnosperms become predominant,

Paleogene

Neogene

Quaternary

Triassic

THE GEOLOGIC TIME SCALE

C. Mesozoic era - which period?

marine organisms diversify, reptiles diversify, first dinosaurs, first mammals.

Paleogene

Neogene

Quaternary

Jurassic

THE GEOLOGIC TIME SCALE

C. Mesozoic era - which period?

______________ (200-145 MYA): Gondwana separates again. Eurasia and North America separate,

Paleogene

Neogene

Quaternary

Jurassic

THE GEOLOGIC TIME SCALE

C. Mesozoic era - which period?

Dinosaurs and other reptiles diversify, first birds, archaic mammals,

Paleogene

Neogene

Quaternary

Jurassic

THE GEOLOGIC TIME SCALE

C. Mesozoic era - which period?

gymnosperms continue to dominate, evolution of angiosperms, “Mesozoic marine revolution”

Paleogene

Neogene

Quaternary

Cretaceous

THE GEOLOGIC TIME SCALE

C. Mesozoic era - which period?

_______________ (145-65.5 MYA): Pangaea had broken up to present day continents,

Paleogene

Neogene

Quaternary

Cretaceous

THE GEOLOGIC TIME SCALE

C. Mesozoic era - which period?

continued radiation of dinosaurs, increasing diversity of angiosperms, mammals, birds,

Paleogene

Neogene

Quaternary

Cretaceous

THE GEOLOGIC TIME SCALE

C. Mesozoic era - which period?

mass extinction in the end (Many groups of organisms, including dinosaurs become extinct at end of the period)

Paleogene

Neogene

Quaternary

Cenozoic

D. _____________ era – “age of mammals”

Paleogene

• Paleocene

THE GEOLOGIC TIME SCALE

D. Cenozoic era - which period and epoch?

____________ (65.5-23 MYA) period

• ____________ (65.5 – 55.8 MYA): cooler and dryer than Cretaceous;

Paleogene

Neogene

Quaternary

Paleogene

• Paleocene

THE GEOLOGIC TIME SCALE

D. Cenozoic era - which period and epoch?

____________ (65.5-23 MYA) period

• ____________ (65.5 – 55.8 MYA): mammals, birds, and pollinating insects became more diverse, many evolved larger body size, adopting ecological roles similar to the now-extinct dinosaurs;

Paleogene

Neogene

Quaternary

Paleogene

• Paleocene

THE GEOLOGIC TIME SCALE

D. Cenozoic era - which period and epoch?

____________ (65.5-23 MYA) period

• ____________ (65.5 – 55.8 MYA): many modern plant species appeared such as cacti and palm trees.

Paleogene

Neogene

Quaternary

Paleogene

• Eocene

THE GEOLOGIC TIME SCALE

D. Cenozoic era - which period and epoch?

____________ (65.5-23 MYA) period

• ____________ (55.8 – 33.9 MYA): climate was warm globally, allowing migration of mammals between continents; 

Paleogene

Neogene

Quaternary

Paleogene

• Eocene

THE GEOLOGIC TIME SCALE

D. Cenozoic era - which period and epoch?

____________ (65.5-23 MYA) period

• ____________ (55.8 – 33.9 MYA): became cooler towards the end – Antarctic ice cap formation;

Paleogene

Neogene

Quaternary

Paleogene

• Eocene

THE GEOLOGIC TIME SCALE

D. Cenozoic era - which period and epoch?

____________ (65.5-23 MYA) period

• ____________ (55.8 – 33.9 MYA): mammals diversified into perissodactyls, artiodactyls, proboscideans, rodents, and primates.

Paleogene

Neogene

Quaternary

Paleogene

• Oligocene

THE GEOLOGIC TIME SCALE

D. Cenozoic era - which period and epoch?

____________ (65.5-23 MYA) period

• ____________ (33.9 - 23 MYA): climate cooled; mammalian diversity decreased; origin of many primate groups including apes

Paleogene

Neogene

Quaternary

Neogene

• Miocene

THE GEOLOGIC TIME SCALE

D. Cenozoic era - which period and epoch?

____________ (23 to 3 MYA) period

• ____________ (23-5.3 MYA): During the later ____________ mammals were more modern, with easily recognizable canids, bears, procyonids, equids, beavers, deer, camelids, and whales;

Paleogene

Neogene

Quaternary

Neogene

• Miocene

THE GEOLOGIC TIME SCALE

D. Cenozoic era - which period and epoch?

____________ (23 to 3 MYA) period

• ____________ (23-5.3 MYA): ape-like ancestors of humans appear

Paleogene

Neogene

Quaternary

Neogene

• Pliocene

THE GEOLOGIC TIME SCALE

D. Cenozoic era - which period and epoch?

____________ (23 to 3 MYA) period

• ____________ (5.3-2.6 MYA): Animals are fairly modern. Origin of genus Homo.

Paleogene

Neogene

Quaternary

Quaternary

• Pleistocene

THE GEOLOGIC TIME SCALE

D. Cenozoic era - which period and epoch?

____________ (3 MYA to present) period

• ____________ (2.6 MYA – 11,700 y.a.): Over 11 major glacial events, as well as many minor glacial events.

Paleogene

Neogene

Quaternary

Quaternary

• Pleistocene

THE GEOLOGIC TIME SCALE

D. Cenozoic era - which period and epoch?

____________ (3 MYA to present) period

• ____________ (2.6 MYA – 11,700 y.a.): Humans (Homo sapiens) appear.

Paleogene

Neogene

Quaternary

Quaternary

• Holocene

THE GEOLOGIC TIME SCALE

D. Cenozoic era - which period and epoch?

____________ (3 MYA to present) period

• ____________ (11,700 y.a. to present)

Paleogene

Neogene

Quaternary

Mass extinctions

It is a phenomenon when extinction rates appear to be exceptionally high, unusually high numbers of taxa become extinct

Ordovician-Silurian extinction

MASS EXTINCTIONS

86%, second largest extinction

Ordovician-Silurian extinction

Late Devonian extinction

Permian-Triassic extinction

Triassic-Jurassic extinction

Cretaceous-Paleogene extinction

Ordovician-Silurian extinction

MASS EXTINCTIONS

Involved massive glaciation – locked up much of the world's water as ice; temperature and sea levels dropped

Ordovician-Silurian extinction

Late Devonian extinction

Permian-Triassic extinction

Triassic-Jurassic extinction

Cretaceous-Paleogene extinction

Ordovician-Silurian extinction

MASS EXTINCTIONS

reduced number of small marine organisms like trilobites, brachiopods, and graptolites

Ordovician-Silurian extinction

Late Devonian extinction

Permian-Triassic extinction

Triassic-Jurassic extinction

Cretaceous-Paleogene extinction

Late Devonian extinction

MASS EXTINCTIONS

75%, due to mass amounts of algal blooms leading to reduced number of sea animals

Ordovician-Silurian extinction

Late Devonian extinction

Permian-Triassic extinction

Triassic-Jurassic extinction

Cretaceous-Paleogene extinction

Permian-Triassic extinction

MASS EXTINCTIONS

Largest mass extinction (~96%) – “The Great Dying”

Ordovician-Silurian extinction

Late Devonian extinction

Permian-Triassic extinction

Triassic-Jurassic extinction

Cretaceous-Paleogene extinction

Permian-Triassic extinction

MASS EXTINCTIONS

Due to an enormous volcanic eruption

• Air was filled with CO₂ which fed different kinds of bacteria

• Bacteria emitted large amounts of methane

• The Earth warmed, and the oceans became acidic

Ordovician-Silurian extinction

Late Devonian extinction

Permian-Triassic extinction

Triassic-Jurassic extinction

Cretaceous-Paleogene extinction

Permian-Triassic extinction

MASS EXTINCTIONS

Ancient coral species were completely lost

Ordovician-Silurian extinction

Late Devonian extinction

Permian-Triassic extinction

Triassic-Jurassic extinction

Cretaceous-Paleogene extinction

Permian-Triassic extinction

MASS EXTINCTIONS

After this event, new marine life emerged

Ordovician-Silurian extinction

Late Devonian extinction

Permian-Triassic extinction

Triassic-Jurassic extinction

Cretaceous-Paleogene extinction

Triassic-Jurassic extinction

MASS EXTINCTIONS

80%, due to an asteroid impact, climate change, and flood basalt eruptions

Ordovician-Silurian extinction

Late Devonian extinction

Permian-Triassic extinction

Triassic-Jurassic extinction

Cretaceous-Paleogene extinction

Triassic-Jurassic extinction

MASS EXTINCTIONS

greatly affected synapsids

• group of amniotes to which mammals belong

Ordovician-Silurian extinction

Late Devonian extinction

Permian-Triassic extinction

Triassic-Jurassic extinction

Cretaceous-Paleogene extinction

Synapsids

These are survivors of the Permian-Triassic extinction that gave rise to the first true mammals during Jurassic period

temporal fenestra

Synapsids are characterized by ____________, a hole behind each eye socket

Synapsids

lineage that eventually gave rise to mammals

Triassic-Jurassic extinction

MASS EXTINCTIONS

extinction of other vertebrate species; allowed dinosaurs to flourish

Ordovician-Silurian extinction

Late Devonian extinction

Permian-Triassic extinction

Triassic-Jurassic extinction

Cretaceous-Paleogene extinction

Cretaceous-Paleogene extinction

MASS EXTINCTIONS

Most well-known, 76%, due to volcanic activity, asteroid impact, climate change

Ordovician-Silurian extinction

Late Devonian extinction

Permian-Triassic extinction

Triassic-Jurassic extinction

Cretaceous-Paleogene extinction

Cretaceous-Paleogene extinction

MASS EXTINCTIONS

Extinction of dinosaurs, ammonites, and many flowering plants

Ordovician-Silurian extinction

Late Devonian extinction

Permian-Triassic extinction

Triassic-Jurassic extinction

Cretaceous-Paleogene extinction

Cretaceous-Paleogene extinction

MASS EXTINCTIONS

Evolution of mammals on land and sharks in the sea

Ordovician-Silurian extinction

Late Devonian extinction

Permian-Triassic extinction

Triassic-Jurassic extinction

Cretaceous-Paleogene extinction

Stromatolites

____________ are layered, biochemical, accretionary structures formed in shallow water by the trapping, binding, and cementation of sedimentary grains in biofilms, through the action of certain microbial lifeforms, especially cyanobacteria.

Impact hypothesis (Alvarez et al. 1980. UC Berkeley)

postulated to be the main cause of the cretaceous extinctions

• collision of an asteroid or a large comet with earth

Impact hypothesis (Alvarez et al. 1980. UC Berkeley)

K-Pg boundary

• Evidence for it is a thin layer of clay enriched in iridium (Ir) separates Mesozoic from Cenozoic sediments

Iridium

___________ - an element very rare on earth but common in meteorites and other extraterrestrial debris

• can come from volcanic eruptions but asteroids are the most likely accepted explanation

• Geochemical evidence: Iridium anomaly

• Geological structure: Chicxulub crater

• Physical structures generated by the impact

• Suddenness and synchroneity of extinctions

Possible pieces of evidence for the Asteroid Impact Theory:

• __________________________

• __________________________ (65 myo) on the Yucatan coast of Mexico

  • about 180 km in diameter - about the right size to have been caused by an asteroid with a diameter of about 10 km.

• __________________________:

  • rocks suggestive of a high-velocity collision have been found

  • e.g. shocked tektites and quartzes at K/T sites and at Chicxulub

• ___________________________:

  • Extinctions should:

    • have been sudden & concentrated in a short interval of time

    • be synchronous in different taxa and geographic localities

  • evidence not complete enough to pursuade all.

Death of so many species from their ecosystems due to mass extinctions reduce competition for resources and leave behind many vacant niches, which surviving lineages can evolve into.

What is the Importance of mass extinctions?