Download Organization of Life on earth

Its Origin and Evolution
Levels of Organization
Biosphere
 Ecosystems
 Communities
 Populations
 Organisms
 Organs and Organ Systems
 Tissues
 Cells
 Organelles
 Molecules

Levels of Organization
Biosphere

Everywhere within the Earth’s
atmosphere where life exists.
Ecosystems

The biotic and abiotic factors within an
environment
 Interactions between organisms
 Interactions between organisms and the
environment
 Cycling of Nutrients
 Energy flow
Community

All living organisms in a particular region
Population

All individuals of a species in a particular
area
Organism

A single living thing
Organs & Organ Systems

Organ
 Specialized body parts made of tissues
 Tissues work together to perform a specific
function

Organ System
 Groups of organs that work together to
perform specific functions
Tissue

A group of similar cells
Cell

Basic unit of:
 Life
 Structure and function

Contains DNA
Organelle

Structural component of a cell
Molecule

Chemical structure consisting of atoms
Diversity of Life

Domain Bacteria
 Prokaryotic

Domain Archaea
 Prokaryotic
 Live under extreme conditions

Domain Eukarya
 Protists (unicellular eukaryotes)
 Kingdom Plantae (photosynthetic)
 Kingdom Fungi (decomposers)
 Kingdom Animalia (ingest others)
Evolution

On the Origin of Species, Charles
Darwin
 Contemporary species arose from a
succession of ancestors
○ “descent with modification”
 Natural Selection
○ Mechanism for descent with modification
Early Earth & the Origin of Life

Chemical and physical processes on
early Earth may have produced very
simple cells through a sequence of
stages:
1. Abiotic synthesis of small organic molecules
2. Joining of these small molecules into
polymers
3. Packaging of molecules into “protobionts”
4. Origin of self-replicating molecules

Earth formed about 4.6 billion years ago

Earth’s early atmosphere contained water
vapor and chemicals released by volcanic
eruptions

Experiments simulating an early Earth
atmosphere produced organic molecules
from inorganic precursors, but such an
atmosphere on early Earth is unlikely
CH4
Water vapor
Electrode
Condenser
Cold
water
H2O
Cooled water
containing
organic
molecules
Sample for
chemical analysis
Other Explanations

synthesis near submerged volcanoes
and deep-sea vents
Other Explanations

Extraterrestrial Sources
 Carbon compounds have been found in
some meteorites that landed on Earth
Abiotic Synthesis of Polymers

Small organic molecules polymerize when
they are concentrated on hot sand, clay, or
rock

Protobionts
 aggregates of abiotically produced molecules
surrounded by a membrane or membrane-like
structure
 could have formed spontaneously from abiotically
produced organic compounds
○ Example: small membrane-bounded droplets called
liposomes can form when lipids or other organic
molecules are added to water

The first genetic material was probably RNA,
not DNA

RNA molecules called ribozymes have been
found to catalyze many different reactions,
including:
 Self-splicing
 Making complementary copies of short stretches of
their own sequence or other short pieces of RNA

Early protobionts with self-replicating, catalytic
RNA would have been more effective at using
resources and would have increased in
number through natural selection
Fossils

Formation





Sedimentary rocks
Low humidity
Ice
Amber
Dating
 Strata & Index Fossils
○ Relative Dating
 Radiometric Dating
○ Absolute Dating
 Paleomagnetism
Ratio of parent isotope
to daughter isotope
Accumulating
“daughter”
isotope
1
2
Remaining
“parent”
isotope
1
1
4
1
2
Time (half-lives)
3
8
1
4
16
Fossils
Benefits
Limitations
•Preserved remains
•Previous life
•Ancestral connections
•Evolutionary patterns
•Migration patterns
•Geographic/environmental history
•Major changes
•Exact dates
•Incomplete
•Habits
•Behavior
•Chemical composition
•Color
•Texture
•Internal anatomy and physiology
Animation: The Geologic Record
Cenozoic
Humans
Land plants
Animals
Origin of solar
system and
Earth
1
4
Proterozoic
Eon
Multicellular
eukaryotes
Archaean
Eon
Billions of years ago
2
3
Prokaryotes
Single-celled
eukaryotes
Atmospheric
oxygen
Geologic Time Scale

Each era is a distinct age in the history
of Earth and its life, with boundaries
marked by mass extinctions seen in the
fossil record
 Occasions when global environmental
changes were so rapid and disruptive that a
majority of species were swept away

Lesser extinctions mark boundaries of
many periods within each era
600
Millions of years ago
400
300
200
500
100
0
100
2,500
80
Number of
taxonomic
families
Permian mass
extinction
2,000
Extinction rate
60
1,500
40
Cretaceous
mass extinction
20
1,000
Paleozoic
Mesozoic
Cenozoic
Neogene
Paleogene
Cretaceous
Jurassic
Triassic
0
Permian
Devonian
Silurian
Ordovician
Cambrian
Proterozoic eon
0
Carboniferous
500
Mass Extinctions

Permian
 Killed about 96% of marine animal species
and 8 out of 27 orders of insects
 Cause = volcanic eruptions

Cretaceous
 Killed many marine and terrestrial
organisms, notably the dinosaurs
 Cause = meteor impact

Mass extinctions = opportunities for
adaptive radiations
Early Life

Oldest known fossils are stromatolites
 rocklike structures composed of many layers
of bacteria and sediment
 Date back 3.5 billion years

Prokaryotes were Earth’s sole
inhabitants from 3.5 to about 2 billion
years ago
Electron Transport Systems

Produce ATP (adenosine triphosphate)
from ADP (adenosine diphosphate)
Photosynthesis

Oxygenic photosynthesis probably evolved
about 3.5 billion years ago in cyanobacteria

Effects of oxygen accumulation in the
atmosphere about 2.7 billion years ago:
 Posed a challenge for life
 Provided opportunity to gain energy from light
 Allowed organisms to exploit new ecosystems
Eukaryotic Life
Oldest fossils of eukaryotic cells date
back 2.1 billion years
 theory of endosymbiosis

Cytoplasm
DNA
Plasma
membrane
Ancestral
prokaryote
Infolding of
plasma membrane
Endoplasmic reticulum
Nuclear envelope
Nucleus
Engulfing of aerobic
heterotrophic
prokaryote
Cell with nucleus
and endomembrane
system
Mitochondrion
Mitochondrion
Ancestral
heterotrophic
eukaryote
Engulfing of
photosynthetic
prokaryote in
some cells
Plastid
Ancestral
photosynthetic eukaryote
Evidence for Endosymbiosis
Similarities in inner membrane
structures and functions
 Both have their own circular DNA

Multicellular Eukaryotes
The common ancestor of multicellular
eukaryotes dates back 1.5 billion years
 Larger organisms do not appear in the
fossil record until several hundred
million years later

Multicellular Eukaryotes

Colonies
 collections of autonomously replicating cells
 Some cells became specialized for different
functions
The “Cambrian Explosion”

Most of the major phyla of animals
 Cnidaria and Porifera date back to the late
Proterozoic

Molecular evidence suggests that many
animal phyla originated and began to
diverge between 1 billion and 700 million
years ago
Early
Paleozoic
era
(Cambrian
period)
Late
Proterozoic
eon
Millions of years ago
542
Arthropods
Molluscs
Annelids
Brachiopods
Chordates
Echinoderms
Cnidarians
Sponges
500
The Move to Land

Plants, fungi, and animals colonized
land about 500 million years ago

Symbiotic relationships
Eurasian Plate
North
American
Plate
Juan de Fuca
Plate
Philippine
Plate
Caribbean
Plate
Arabian
Plate
Indian
Plate
Cocos Plate
Pacific
Plate
Nazca
Plate
South
American
Plate
Scotia Plate
African
Plate
Antarctic
Plate
Australian
Plate
Volcanoes and
volcanic islands
Trench
Oceanic ridge
Cenozoic
0
By the end of the
Mesozoic, Laurasia
and Gondwana
separated into the
present-day continents.
65.5
Mesozoic
135
251
Paleozoic
Millions of years ago
By about 10 million years
ago, Earth’s youngest
major mountain range,
the Himalayas, formed
as a result of India’s
collision with Eurasia
during the Cenozoic.
The continents continue
to drift today.
By the mid-Mesozoic
Pangaea split into
northern (Laurasia)
and southern
(Gondwana)
landmasses.
At the end of the
Paleozoic, all of
Earth’s landmasses
were joined in the
supercontinent
Pangaea.
Tree of Life
The five kingdom system has been replaced
by three domains: Archaea, Bacteria, and
Eukarya
 Each domain has been split into kingdoms

 Kingdom
 Phylum
 Class
 Order
 Family
 Genus
 Species
Domain Archaea
Domain Bacteria
Universal ancestor
Domain Eukarya
Charophyceans
Chlorophytes
Red algae
Cercozoans, radiolarians
Stramenopiles (water molds, diatoms, golden algae, brown algae)
Alveolates (dinoflagellates, apicomplexans, ciliates)
Euglenozoans
Diplomonads, parabasalids
Euryarchaeotes, crenarchaeotes, nanoarchaeotes
Korarchaeotes
Gram-positive bacteria
Cyanobacteria
Spirochetes
Chlamydias
Proteobacteria
Chapter 27
Chapter 28
Plants
Fungi
Animals
Bilaterally symmetrical animals (annelids,
arthropods, molluscs, echinoderms, vertebrates)
Chapter 32
Cnidarians (jellies, coral)
Sponges
Chapter 31
Choanoflagellates
Club fungi
Sac fungi
Chapter 28
Arbuscular mycorrhizal fungi
Zygote fungi
Chytrids
Chapter 30
Amoebozoans (amoebas, slime molds)
Angiosperms
Gymnosperms
Seedless vascular plants (ferns)
Bryophytes (mosses, liverworts, hornworts)
Chapter 29
Chapters 33, 34
Theories of Evolution

Gradualism
 Hutton & Lyell

Lamarck
 Use and Disuse

Darwin
 On the Origin of Species
 Descent with Modification
○ Common Ancestors
 Natural Selection
Natural Selection

How do environmental changes affect a
population?
Cactus eater. The long,
sharp beak of the
cactus ground finch
(Geospiza scandens)
helps it tear and eat
cactus flowers and
pulp.
Seed eater. The large
ground finch (Geospiza
magnirostris) has a large
beak adapted for cracking
seeds that fall from plants
to the ground.
Insect eater. The green warbler finch
(Certhidea olivacea) used its narrow,
pointed beak to grasp insects.
LE 22-11
A flower mantid
in Malaysia
A stick mantid
in Africa
Natural Selection

Antibiotic Resistance
Ernst Mayer

Observation #1:
 For any species, population sizes would increase
exponentially if all individuals that are born reproduced
successfully

Observation #2:
 Populations tend to be stable in size, except for
seasonal fluctuations

Observation #3:
 Resources are limited

Inference #1:
 Production of more individuals than the environment can
support leads to a struggle for existence among
individuals of a population, with only a fraction of their
offspring surviving

Observation #4:
 Members of a population vary extensively in their
characteristics; no two individuals are exactly
alike

Observation #5:
 Much of this variation is heritable

Inference #2:
 Survival depends in part on inherited traits;
individuals whose inherited traits give them a high
probability of surviving and reproducing are likely
to leave more offspring than other individuals

Inference #3:
 This unequal ability of individuals to survive
and reproduce will lead to a gradual change
in a population, with favorable
characteristics accumulating over
generations
Artificial Selection
Artificial Selection
Terminal
bud
Lateral
buds
Brussels sprouts
Cabbage
Leaves
Flower
clusters
Kale
Cauliflower
Stem
Flowers
and
stems
Broccoli
Wild mustard
Kohlrabi
Evidence for Evolution

Homology (homologous structures)
Human
Cat
Whale
Bat
Homologous Plant Structures
Evidence for Evolution
LE 22-15

Comparative Embryology
 Shows homologies not visible in adult forms
Pharyngeal
pouches
Post-anal
tail
Chick embryo (LM)
Human embryo
Evidence for Evolution

Vestigial Structures
 Remnants of structures once used in
ancestors
Evidence for Evolution

Molecular Homologies (similar biochemistry)
 Similarities in protein structure and genes
LE 22-16
Species
Percent of Amino Acids That Are
Identical to the Amino Acids in a
Human Hemoglobin Polypeptide
Human
100%
Rhesus monkey
95%
87%
Mouse
69%
Chicken
54%
Frog
Lamprey
14%
Some Evidence of Evolution

Biogeography
 similar mammals that have adapted to similar
environments have evolved independently from
different ancestors
LE 22-17
NORTH
AMERICA
Sugar
glider
AUSTRALIA
Flying
squirrel
Evidence of Evolution

Fossil Record
Phylogeny

Phylogeny is the evolutionary history of
a species or group of related species

Systematics
 morphological, biochemical, and molecular
comparisons to infer evolutionary
relationships

Cladistics
Homology vs. Analogy

Similarity due to shared
ancestry

Similarity due to
coevolution
 Adaptation to similar
environments
HOMOLOGY
ANALOGY
LE 25-8
Binomial
Nomenclature
Panthera
pardus
Species
Panthera
Genus
Felidae
Family
Carnivora
Order
Mammalia
Class
Chordata
Phylum
Animalia
Kingdom
Domain
Eukarya
Species
Mephitis
mephitis
(striped skunk)
Lutra lutra
(European
otter)
Genus
Panthera
Mephitis
Lutra
Felidae
Order
Panthera
pardus
(leopard)
Family
LE 25-9
Mustelidae
Carnivora
Canis
familiaris
(domestic dog)
Canis
lupus
(wolf)
Canis
Canidae
Leopard
Turtle
Salamander
Tuna
Lamprey
Lancelet
(outgroup)
TAXA
CHARACTERS
Hair
Amniotic (shelled) egg
Four walking legs
Hinged jaws
Vertebral column
(backbone)
Character table
Turtle
Leopard
Hair
Salamander
Amniotic egg
Tuna
Four walking legs
Lamprey
Hinged jaws
Lancelet (outgroup)
Vertebral column
Cladogram
Section 18-3
Cladogram of Six Kingdoms
and Three Domains
DOMAIN
ARCHAEA
DOMAIN
EUKARYA
Kingdoms
DOMAIN
BACTERIA
Go to
Section:
Eubacteria
Archaebacteria
Protista
Plantae
Fungi
Animalia

Gene Pools
 All genes present in a particular population

Allele Frequencies
 The relative frequencies of genes in a
population
MAP
AREA
CANADA
ALASKA
LE 23-3
Beaufort Sea
Porcupine
herd range
Fairbanks
Fortymile
herd range
Whitehorse
Hardy-Weinberg

describes a population that is not
evolving
 Allele frequency constant
 Genotype constant
segregation and recombination of alleles
are at work
 Mendelian inheritance preserves genetic
variation

LE 23-4
Generation
1
X
CRCR
genotype
Generation
2
Plants mate
CWCW
genotype
All CRCW
(all pink flowers)
50% CW
gametes
50% CR
gametes
come together at random
Generation
3
25% CRCR
50% CRCW
50% CR
gametes
25% CWCW
50% CW
gametes
come together at random
Generation
4
25% CRCR
50% CRCW
25% CWCW
Alleles segregate, and subsequent
generations also have three types
of flowers in the same proportions

If p and q represent the relative
frequencies of the only two possible
alleles in a population at a particular
locus, then
 p2 + 2pq + q2 = 1
○ p2 and q2 (homozygous genotypes)
○ 2pq (heterozygous genotype)

The five conditions for non-evolving
populations:
 Extremely large population size
 No gene flow
 No mutations
 Random mating
 No natural selection
LE 23-7
Genetic Drift
CWCW
CRCR
CRCR
CRCW
Only 5 of
10 plants
leave
offspring
CRCR
CWCW
CRCW
CWCW
CRCR
CRCW
CRCW
CRCR
CRCR
CRCR
CRCW
CRCW
Generation 1
p (frequency of CR) = 0.7
q (frequency of CW) = 0.3
CWCW
CRCR
Only 2 of
10 plants
leave
offspring
CRCR
CRCR
CRCR
CRCR
CRCR
CRCR
CRCR
CRCR
CRCW
CRCW
Generation 2
p = 0.5
q = 0.5
CRCR
CRCR
Generation 3
p = 1.0
q = 0.0
LE 23-8
Bottleneck Effect
Original
population
Bottlenecking
event
Surviving
population
Heterozygote Advantage

Sometimes heterozygotes (at a
particular locus) have greater fitness
than homozygotes
 Ex. Sickle Cell

Natural selection will tend to maintain
two or more alleles at that locus
LE 23-13
Frequencies of the
sickle-cell allele
0–2.5%
2.5–5.0%
5.0–7.5%
Distribution of
malaria caused by
Plasmodium falciparum
(a protozoan)
7.5–10.0%
10.0–12.5%
>12.5%
Types of Selection

Sexual Selection
 Results in sexual dimorphism
 Intrasexual selection - members of one gender
fight against one another for mates of the
opposite gender
○ Usually results from picky mates (usu. Females)
of
Asexual
Reproduction
Pro
Sexual
Reproduction
Con
Pro
Con
LE 23-16
Asexual reproduction
Female
Sexual reproduction
Generation 1
Female
Generation 2
Male
Generation 3
Generation 4
Perfection?
Evolution is limited by historical
constraints
 Adaptations are often compromises
 Chance and natural selection interact
 Selection can only edit existing
variations

Speciation - the origin of new species
 Evolutionary theory

 explain how new species originate and how
populations evolve
Microevolution - adaptations that evolve
within a population(within one gene pool)
 Macroevolution - evolutionary change above
the species level

LE 24-3
Similarity between different species.
Diversity within a species.

Reproductive isolation - impede two
species from producing viable, fertile
hybrids
 prezygotic
 postzygotic
Prezygotic Barriers

Impede mating or hinder fertilization if
mating does occur:
 Habitat (geographic) isolation
○ Two species occupy different habitats, even
though not isolated by physical barriers
 Temporal isolation
○ Species breed at different times of the day,
different seasons, or different years
 cannot mix their gametes
 Ex. orchids
Prezygotic Barriers
 Behavioral isolation
○ Behavioral isolation: Courtship rituals and
other behaviors unique to a species are
effective barriers
Prezygotic Barriers
 Mechanical isolation
○ Mechanical isolation: Morphological
differences can prevent successful mating
Prezygotic Barriers
 Gametic isolation
○ Gametic isolation: Sperm of one species may
not be able to fertilize eggs of another species
Postzygotic Barriers

Postzygotic barriers prevent the hybrid
zygote from developing into a viable, fertile
adult:
 Reduced hybrid viability
○ Genes impair development
 Reduced hybrid fertility
○ sterility
 Hybrid breakdown
○ Some first-generation hybrids fertile
○ offspring of the next generation are feeble or
sterile
LE 24-4a
Prezygotic barriers impede mating or hinder fertilization if mating does occur
Habitat
isolation
Temporal
isolation
Behavioral
isolation
Individuals
of
different
species
Mechanical
isolation
Gametic
isolation
Mating
attempt
HABITAT ISOLATION
Fertilization
TEMPORAL ISOLATION BEHAVIORAL ISOLATION MECHANICAL ISOLATION
GAMETIC ISOLATION
Postzygotic barriers prevent a hybrid zygote from
developing into a viable, fertile adult
Reduced
hybrid
viability
Reduced
hybrid
fertility
Hybrid
breakdown
Viable,
fertile
offspring
Fertilization
REDUCED HYBRID
VIABILITY
REDUCED HYBRID
FERTILITY
HYBRID BREAKDOWN
Speciation
Allopatric
Sympatric
•gene flow is interrupted or
•takes place in geographically
reduced when a population is
overlapping populations
divided into geographically isolated •polyploidy
subpopulations
•One or both populations may
undergo evolutionary change
during the period of separation
LE 24-5
Allopatric speciation
Sympatric speciation
LE 24-13
Time
Gradualism model
Punctuated equilibrium model
Patterns of Evolution

Adaptive Radiation
 The process by which a single species or
small group of species have evolved into
several different forms that live in different
ways.
○ Ex. Dinosaurs were the result of adaptive
radiation of reptiles.
Figure legend: Adaptive
Radiation. Diverging from an
ancestral form, a group of
organisms is suddenly able
to exploit a major new range
of habitats. Within each
smaller habitat, local
selection pressures give rise
to new gene pools adapted
for those conditions.
If these groups eventually
become reproductively
isolated, they may become
new species.
Adaptive Radiation
Patterns of Evolution

Convergent Evolution
 The process by which unrelated organisms
come to resemble one another.
○ Ex. Penguins and Dolphins
Patterns of Evolution

Coevolution
 The process by which two species evolve in
response to changes in each other over time
○ Ex. Hummingbird and some plants with
flowers
Coevolution
Coevolution