Transcript Change through Time…………… …Evolution.. Chpt 17/18

HONORS BIOLOGY
Chapters 17, 20 & 21
Emergence of Evolutionary
Thought and
the Origin and Evolution
of Life
Important Dates
13700 MYA
12000 MYA
4600 MYA
3500 MYA
2100 MYA
1500 MYA
535-525 MYA
500 MYA
420 MYA
365 MYA
6-7 MYA
THE BIG BANG (UNIVERSE IS BORN)
THE FORMATION OF THE MILKY WAY GALAXY
THE FORMATION OF OUR SOLAR SYSTEM AND THE EARTH
FIRST FOSSIL EVIDENCE OF LIFE ON EARTH (STROMATOLITES,
EARLY PROKARYOTES
FIRST FOSSIL EVIDENCE OF EUKARYOTIC CELLS
EARLIEST MULTICELLULAR EUKARYOTES
CAMBRIAN EXPLOSION
CNIDARIA (SEA ANEMONES AND THEIR RELATIVES)
PORIFERA (SPONGES)
MOLLUSCA (SHELLFISH)
THE COLONIZATION OF THE LAND (FUNGI, PLANTS AND ANIMALS)
SMALL PLANTS WITH A VASCULAR SYSTEM (LACKED TRUE ROOTS OR
LEAVES)
TETRAPODS (EVOLVED FROM LOPE-FINNED FISHES) AND INSECTS
HUMAN LINEAGE DIVERGED FROM OTHER HOMINOIDS (APES)
*** IF THE CLOCK OF EARH’S HISTORY WERE RESCALED
TO REPRESENT AN HOUR, HUMANS APPEARED LESS THAN
0.2 SECONDS AGO.
Early thoughts on biological
diversity………..
• Aristotle - believed nature to be a continuum of organization….a
GREAT CHAIN OF BEING……extending from the lowest
forms of life to humans and then to the spiritual world. Each kind
of organism was a “species”.
• “Each being (species) had a fixed place in the divine order;
unchanged & unchanging since creation.”
• It was believed that all organisms were formed at the same time
and had not changed since.
• Once all organisms were identified, the meaning of life would be
revealed!!
Biogeography …………...
• The study of the distribution of plants and animals
worldwide and the types of climates and geographic
barriers that affect gene flow.
• Global voyages (16th century) led to many questions of
when new species fit into the “Great Chain of Being.”
• Why are certain species found in only some parts of the
world, but not others? How did certain species get from
the Center of Creation to islands & isolated places?
• Biologists began to wonder if there is a relationship
between life forms and the geography of the land.
The Theory of …………………..
Spontaneous Generation
• Before the microscope, it
was commonly believed
that life arose from nonliving materials!
• Flies came from rotting
meat.
• Bacteria came from
rotting broth.
• Frogs came from rain &
mud.
• Mice came from grain &
rags.
• Francesco Redi disproved the idea that
flies came from rotting
meat.
• Louis Pasteur
disproved the idea that
bacteria spontaneously
arose from broth.
• BIOGENESIS- Life
must arise only from
living organisms.
Pasteur’s
Experiment
If life comes from life….
where or how did the first life
form arise?
• Simple organic molecules and the
organization of these molecules into more
complex substances would have occurred.
• Early Earth’s atmosphere did not contain
free oxygen. (water vapor, hydrogen,
methane, and ammonia)
• Life would have to occur under very
difficult conditions- different from today!
Alexander Oparin’s Theory
• As the earth cooled, life began in the oceans
as organic molecules slowly assembled.
• Energy from sun and lightning could have
triggered chemical reactions to produce
simple organic compounds, creating a
primordial soup.
Complex Organic Compounds
• 1953 - Miller and Urey set up experiment
simulating conditions of early Earth
• Their experiment produced amino acids,
sugars, and other organic compounds.
• Similar processes have produced ATP
(energy carrier) and nucleotides (building
blocks of DNA).
• MILLER - UREY
EXPERIMENT
• CH4, NH3, and H2
represented the
primitive
atmosphere. Along
with water vapor and
electrical chargesorganic molecules
were produced...
The Evolution of Cells
• Must be able to survive in harshest of climates
(sulfur springs, extreme heat, little light or oxygen).
• First organisms were:
– prokaryotic
– anaerobic
– heterotrophic
• Similar to oldest organisms - Archaebacteria
• Evolved into autotrophs; photosynthetic (oxygen)
• Presence of oxygen also created ozone.
Early Evolutionary Theories….
• Georges Cuvier:
– (Anatomist) compared the body plans of fossils and living
organisms.
– noted abrupt changes in the fossil record that
corresponded to changes in the sedimentary layers of
the earth.
– Theory of Catastrophism:
• all life was created at the same time
• a series of global catastrophes occurred
• proposed that today’s species are descendants of the
survivors of those catastrophes.
The Theory of Acquired Characteristics
• Jean-Baptiste de Lamarck :
– stated that environmental pressures and internal desires
brought about permanent changes in an organism.
– internal force to change is a drive for perfection
up the Chain of Being.
– fluida: substance in the nerves
– EXAMPLE: Giraffe’s neck slowly became
longer.
• environmental changes
• fluida within the animal, so its offspring are born with
longer necks.
The Theory of Evolution of Life
• Charles Darwin -A Naturalist who, in 1831, traveled
on the “HMS Beagle” for a five year expedition to
collect, study, and store biological specimens
discovered.
• Principles of Geology by Charles Lyell -stated the
Theory of Uniformity (geological changes happen at a
uniform gradual rate over time, making the Earth very
old; millions not thousands of years old.)
• Thomas Malthus -A study of over-population;
‘survival of the fittest’; not all competing members
survive.
The Galapagos Islands
• Darwin observed many
islands with great
biodiversity.
• Animals and plants were
best suited for their own
particular climate and food
source.
• He noticed that the organisms
on the Galapagos Islands were
similar to those on the mainland
but seemed to have adapted in
different ways in order to
survive each island’s unique
climate and food sources.
• Reasoned: ‘a population is
evolving when its heritable
traits are changing through
successive generations’.
The Galapagos Islands
Was it
possible…
..that these
two
organisms
were related?
If so, how &
why did one
change into
the other?
Darwin’s Finches
Darwin Finches:
• Why are the
Galapagos finches
different from the
same species of
mainland finches?
• What caused the
changes?
•
Darwin’s Theory of……………….
Natural Selection
1. Organisms produce
more offspring than can
survive. (limited food)
• 2. Variations exist within
populations
• 3. Some variations are
more advantageous than
others (struggle for
existence)
• 4. The “fittest” survive
and reproduce! Thus the
species modifies itself
over time. (Natural
Selection)
Artificial Selection vs.
Natural Selection
• Artificial Selection - By breeding organisms that had
desirable traits, their offspring would inherit these same
traits. This process is controlled by man.
• Natural Selection - Nature selects or chooses which traits
in an organism will be passed on to future generations.
Beneficial adaptations are passed on, harmful
adaptations are eliminated.
Adaptations
Adaptation: an
anatomical,
physiological, or
behavioral trait that
improves an
organism’s ability to
survive and
reproduce.
Adaptations
• Populations adapt as the
environment changes
– 1) Mimicry…..A structural
adaptation that provides protection
by enabling an organism to copy
another species. (Monarch and
Viceroy)
– 2) Camouflage….. A structural
adaptation that enables the
organism to blend in with its
environment.
– (Kettlewell’s Peppered Moths)
– 3) Physiological Adaptations….
Bacteria that have developed a
resistance to antibiotics.
monarch
viceroy
Five Points of Evidence for Evolution
• 1. Fossils: Evidence of Ancient
Life
– Fossilization is a slow process (what
does it take to make a fossil?)
– Stratification
• Layering of sedimentary deposits
• The older the layer, the older the fossils
and they are similar on each continent.
– Geologic Time Scale
• Based on sequences of fossils in
sedimentary rocks (bases of Geologic
Time Scale)
•2.Comparative
Morphology: a
comparison of body
forms and structure.
a) Morphological
divergence
(Homologous
structures – Body
parts with similar
structure but different
functions. Ex: arm of
human & forelimb of
bat.)
4
STEM REPTILE
2
1
3
PTEROSAUR
CHICKEN
1
BAT
1
PORPOISE
4
3
5
PENGUIN
3
HUMAN
Fig. 20.4, p. 314
Five Points of Evidence for Evolution
b) Morphological convergence (Analogous structures - Body
parts similar in function but different in structure. Ex:
wings of birds and butterflies.
Comparing Convergent and
Divergent Evolution
jawless
fishes
class
Chondrichthyes
(cartilaginous
fishes)
landdwelling
stem
reptiles
shark
class
Reptilia
(reptiles)
class Mammalia
(mammals)
pectoral fin
class
Aves
(birds)
penguin
flipper (derived from a
wing)
These parts all function similarly, but probably developed because
of common environmental pressures. Natural selection probably
flipper (derived from a foreleg)
porpoise
caused similar
modifications.
Fig. 20.5, p. 315
Vestigial Features
3. Vestigial Organs Structures that have no
function in the organism
today but may have been
useful at one time.
Example: appendix
pelvic girdle (hind
legs attach to these)
coccyx (bones
where many
other mammals
have a tail)
small bone
thighbone
attached to
attached to
pelvic girdle
pelvic girdle
Similarities in Embryology
Five Points of Evidence for Evolution
4. Comparative Embryology – early vertebrate
embryos strongly resemble one another.
– WHY?
– They inherited the same ancient plan for development.
– Then, how did adults of different groups get to be so
different?
• Heritable changes in the onset, rate or time of completion of
developmental steps which could increase or decrease relative
size of tissue or organs.
FISH
REPTILE
adult shark
BIRD
(chicken)
MAMMAL
(human)
Early human embryo (three
millimeters in length)
Fig. 20.7, p. 317
Changes in timing of
developmental steps
• Britten and Reynolds
hypothesized that transposons
brought about variation among
lineages.
– Transposons: DNA segments
move spontaneously from 1
location to another on the same or
different chromosome.
Which one of the infant
– They often deactivate genes
skulls is an ape?
– Can cause interesting traits
Five Points of Evidence for Evolution
• 5. Evidence from Comparative Biochemistry (Genetic
Similarities) - DNA and RNA sequences are similar in
related organisms.
– Molecular clocks: neutral mutations (no affect on survival &
reproduction rates; can be used to date times of divergence of
species.
– Protein comparisons
• amino acid sequence in DNA
• Cytochrome C (used to place humans, chimps, rhesus monkeys)
– Nucleic Acid comparisons (base-pairing of DNA/RNA from one
species to another)
3 Versions of Cytochrome C (a major component
of electron transport systems in cells)
• The 3 amino sequences about are; yeast, wheat and a primate.
•What do the colors indicate?
•GOLD = SEQUENCES OF AMINO ACIDS THAT ARE
IDENTICAL IN ALL 3 SPECIES.
DNA-DNA Hybridization Studies
• comparing 2 stands of DNA from 2 different species
• measuring heat of separation (more heat, related)
RACCOON
RED PANDA
GIANT PANDA
DIVERGENCE
15-20 million years ago
DIVERGENCE
approximately
40 million years ago
SPECTACLED
BEAR
SUN
SLOTH
BEAR
BEAR
BLACK
BEAR
POLAR BROWN
BEAR
BEAR
What about the “missing links”?
If each species evolved from
others, where were the fossils of
the transitional species?
In 1860, the fossilized skeleton of
Archaeopteryx was found in
Germany. It was the first of many
transitional fossils to be found,
demonstrating how one species
had lead to another.
Dromaeosaurus
Archaeopteryx
Mechanisms of Evolution
• Evolution occurs when there is a change in
the genetic makeup of a population.
• Evolution occurs in a population over many
generations, and thus is a very slow process.
• Gene pool - all the genes in a population
• Allele frequency - Proportion of each allele
in a gene pool (SS,Ss, Ss, ss - 3:1 spotted to
black)
Changes in Genetic Equilibrium
• Genetic equilibrium - Allele frequencies do
not change over time (non–evolving)
1) Mutations - Cause genetic changes in
gene pool.
2) Genetic Drift - Changes due to chance
events (Small populations)
3) Gene flow - Movement of genes into
or out of a population
Speciation
• The formation of a new species from an ancestral form (species
only mate with each other).
• This can only occur when inter-breeding or the production of
fertile offspring is somehow prevented.
• Physical barriers - new mountain ranges, canyons, or water
barriers can create geographical isolation.
• Reproductive Isolation -either by mutations that prevent offspring
development, or seasonal mating changes that prevent mating.
• Speciation can occur quickly or slowly.
• Gradualism- Species originate through a gradual
accumulation of adaptations.
• Punctuated Equilibrium - Occurs in rapid bursts
with long periods of stability in between.
• Adaptive Radiation - An ancestral species
evolves into many different species( Divergent
Evolution)
• Convergent Evolution -Distantly related
organisms evolve similar traits. Ex. whales and
fish……………………………………..el fin !