AP Biology
The History of Life:
Origin of solarsystem andEarth
ProkaryotesAtmospheric oxygen
Hadean
Archaean
4
3
Proterozoic
Animals
MulticellulareukaryotesSingle-celledeukaryotes
2
1
Colonizationof land
Humans! The geologic record is divided into the Hadean, Archaean, Proterozoic, and Phanerozoic eons
! The Phanerozoic eon includes the last half billion years
! The Phanerozoic is divided into three eras: the Paleozoic, Mesozoic, and Cenozoic
! Major boundaries between eras correspond to major extinction events in the fossil record
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Key Events in Origin of Life:! Key events in
evolutionary history of life on Earth" life originated
3.5–4.0 bya
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Prokaryotes:! Prokaryotes dominated life
on Earth from 3.5–2.0 bya! Had ETC; chemiosmotic mechanism
for ATP synthesis
3.5 billion year old fossil of bacteria modern bacteria
chains of one-celledcyanobacteria
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Stromatolites:Fossilized mats of prokaryotes resemble modern microbial colonies
Lynn Margulis
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Oxygen atmosphere: age of oxygen! Oxygen begins to accumulate 2.7 bya
" reducing ® oxidizing atmosphere! evidence in banded iron in rocks = rusting! makes aerobic respiration possible
" photosynthetic bacteria (blue-green algae)
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First Eukaryotes:! Development of internal membranes
" create internal micro-environments" advantage: specialization = increase efficiency
! natural selection!
infolding of theplasma membrane
DNA
cell wall
plasmamembrane
Prokaryoticcell
Prokaryotic ancestor of eukaryotic
cells
Eukaryoticcell
endoplasmicreticulum (ER)
nuclear envelope
nucleus
plasma membrane
~2 bya
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Endosymbiosis:
Eukaryotic cellwith mitochondrion
internal membrane system aerobic bacterium mitochondrion
Endosymbiosis
! Evolution of eukaryotes" origin of mitochondria" engulfed aerobic bacteria, but
did not digest them" mutually beneficial relationship
! natural selection!
Ancestral eukaryotic cell
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mitochondrion
chloroplast
Eukaryotic cell withchloroplast & mitochondrion
Endosymbiosis
photosyntheticbacterium
Endosymbiosis:! Evolution of eukaryotes
" origin of chloroplasts" engulfed photosynthetic bacteria,
but did not digest them" mutually beneficial relationship
! natural selection!
Eukaryoticcell with
mitochondrion
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! Evidence" structural
! mitochondria & chloroplasts resemble bacterial structure
" genetic! mitochondria & chloroplasts
have their own circular DNA, like bacteria" functional
! mitochondria & chloroplasts move freely within the cell
! mitochondria & chloroplasts reproduce independently from the cell
Theory of Endosymbiosis:
Lynn Margulis
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Biologists Discover How Viruses Hijack Cell’s MachineryJan 12, 2017 WOW! Way Cool Stuff @UCSD
ucsdnews.ucsd.edu/.../biologists_discover_how_viruses_hijack_cells_machineryCould this be how multicellular organisms evolved? One existing theory, called “viral
eukaryogenesis,” suggests that the first eukaryotic cell was created when a large virus took over a bacterium. Eventually, the bacterium and virus formed a compound cell, in which the
virus evolved into the nucleus. “It may be too early to know if this particular virus is an intermediate step in the transition from bacteria and viruses to multicellular eukaryotes, but
this discovery could broaden knowledge about the origins of life as we know it,” said Pogliano.
Cryo-electron tomography shows how the bacterial cell is reorganized to resemble a more complicated plant or animal cell with a red nucleus-like compartment and ribosomes, the smaller light blue structures. The reproducing viruses appear with dark blue heads and pink tails. Image by Vorrapon Chaikeeratisak, Kanika Khanna, Axel Brilot, Katrina Nguyen
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! Diversification of Animals" within 10–20 million years most of the major phyla of
animals appear in fossil record
“Cambrian explosion” with a very long fusePaleozoic Era: Cambrian period
543 mya
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Cambrian Period• 543-490 mya
•Many animal phyla
• Trilobites and sponges
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Ordovician Period
• 490-443 mya
• Trilobites, mollusks,
crinoids, corals
•Colonization of land by diverse plants, fungi &
animals
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Silurian Period• 443-417 mya
• Fishes, coral reefs, plants
•Diversification of many vascular
land plants
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More diversity during age of reptiles than there is
now!
Mesozoic Era: Triassic & Jurassic period
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Commonancestor oflineages Aand B
Lineage ALineage B
†
†
†
†
†
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3 24 1 0Millions of years ago
The rise and fall of groups of organisms reflect differences in speciation and extinction rates:• The history of life on Earth has seen
the rise and fall of many groups of organisms
• The rise and fall of groups depends on speciation and extinction rates within the group. The rise of a group of organisms occurs when more new species are produced than are lostto extinction.
Such changes in the fates of specieshas been due to large-scale processes such as plate tectonics,mass extinction & adaptive radiation
Species diversity of an evolutionary lineage will increase when more new member species originate than are lost to extinction. In this example, by 2 mya both Lineage A and B have given rise to four sp., and no sp. have become extinct. By time 0, Lineage A contains only one sp., while Lineage B contains eight sp.
Extinct (†).
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Plate Tectonics: Crustal plates float on lower fluid mantle! Tectonic plates
move slowly through the process of continental drift
! Oceanic and continental plates can collide, separate, or slide past each other
! Interactions between plates cause the formation of mountains and islands, and earthquakes
Formation of the supercontinent Pangaea about 250 million years ago had many effects:
" A deepening of ocean basins" A reduction in shallow water habitat" A colder and drier climate inland
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Continental Drift is an ongoing process:
Continental drift has many effects on living organisms:" A continent’s climate can change as it moves north or south" Separation of land masses can lead to allopatric speciation
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The distribution of fossils and living groups reflects the historic movement of continents:
" For example, the similarity of fossils in parts of South America and Africa is consistent with the idea that these continents were formerly attached
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Cambrian explosion
Diversity of life & periods of 5 Mass Extinction:
*The fossil record shows that most species that have ever lived are now extinct*Extinction can be caused by changes to a species’environment*At times, the rate of extinction has increased dramatically and caused a mass extinction*Mass extinction is the result of disruptive global environmental changes
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The Chicxulub impact crater in the Caribbean Sea near the Yucatan Peninsula of Mexico indicates an asteroid or comet struck the earth and changed conditions 65 million years ago. Dust clouds caused by the impact would have blocked sunlight and disturbed global climate.
Cretaceous extinction:
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Consequences of Mass Extinctions:! Mass extinction can alter ecological communities and the niches
available to organisms! It can take from 5 to 100 million years for diversity to recover following
a mass extinction! Mass extinctions can change the types of organisms found in
ecological communities" For example, the percentage of marine organisms that were
predators increased after the Permian and Cretaceous mass extinctions
! Lineages with novel and advantageous features can be lost during mass extinctions
! By eliminating so many species, mass extinctions can pave the way for adaptive radiations e.g., mammals replace dinosaur niche
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The fossil record shows that diversity of life has increased over the past 250 million yrs. (blue line). This increased is fueled by adaptive radiation.
Adaptive Radiations:the rapid evolution of diversely adapted species from a common ancestorAdaptive radiations may follow:• Mass extinctions(red line)• The evolution of novel
characteristics making them more adaptable to vacant niches
• The colonization of new regions where they face little competition from other species
Mass Extinction and Diversity of Life
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Worldwide Adaptive Radiations:! Mammals underwent an adaptive radiation after the
extinction of terrestrial dinosaurs ! The disappearance of dinosaurs (except birds) allowed for
the expansion of mammals in diversity and size! Other notable radiations include photosynthetic prokaryotes,
large predators in the Cambrian, land plants, insects, and tetrapods. All three radiations are major evolutionary innovations for living on land Ancestral
mammal
ANCESTRALCYNODONT
Monotremes(5 species)
Marsupials(324 species)
Eutherians(placentalmammals;5,010 species)
050100150200250Time (millions of years ago)
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! 125 mya mammals began to radiateout & fill niches
Early mammal evolution:
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Regional Adaptive Radiations:
Dubautia waialealae
Dubautia laxa
Dubautia scabra
Dubautia linearis
Argyroxiphiumsandwicense
HAWAII
MAUILANAI
MOLOKAI
KAUAI
1.3millionyears
0.4millionyears
3.7millionyears
OAHU
5.1millionyears
Close North Americanrelative, the tarweedCarlquistia muirii
! Can occur when organisms colonize new environments with little competition
! The Hawaiian Islands are one of the world’s great showcases of regional adaptive radiation
Molecular analysis indicates that these varied plants known as “silversword alliance” are all descended from an ancestral tarweed that arrived on the islands ~ 5mya from N. America. Members of the silversword alliance have since spread into different habitats and formed new species with different adaptations from island to island where they face very little competition.
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Chimpanzee infant
Chimpanzee fetus
Human fetus Human adult
Chimpanzee adult
Chimpanzee adult
Major changes in body form can result from changes in the sequences and regulation of developmental genes:Effects of Developmental Genes! Genes that program development
control the rate, timing, and spatial pattern of changes in an organism’s form as it develops into an adult
! Heterochrony is an evolutionary change in the rate or timing of developmental events
! It can have a significant impact on body shape
The contrasting shapes of human and chimpanzee skulls are the result of small changes in relative growth rates
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Classifying Life:! Molecular data
challenges 5 Kingdoms! Monera was too diverse
# 2 distinct lineages of prokaryotes! Protists are still too diverse
# not yet sorted out
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OLD SCHOOL CLASSIFICATION
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3 Domain system:! Domains = “Super” Kingdoms
" Bacteria" Archaea
! extremophiles = live in extreme environments# methanogens# halogens# thermophiles
" Eukarya! eukaryotes
# protists# fungi# plants# animals
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KingdomProtista
KingdomFungi
KingdomPlantae
KingdomAnimalia
KingdomArchaebacteria
KingdomBacteria
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Key events in life’s history:3.5 billion years
ago (bya):First prokaryotes
(single-celled)
1.8 bya:First eukaryotes(single-celled)
1.2 bya:First
multicellulareukaryotes
500 mya:Colonization
of land by fungi, plants, and animals
535–525 mya:Cambrian explosion
(great increase in diversityof animal forms)
Millions of years ago (mya)4,000 3,500 3,000 2,500 2,000 1,500 1,000 500
Present
*Turn the clock back 48 hours = Early Earth*Last 20 minutes = dinosaurs*Last 2 seconds = cell phones
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In the last 2 hours we sure have made a mess of things.