Transcript The Origin of Life and Evolution

The Origin of Life
Spontaneous Generation - Organisms
arise from nonliving matter.
EX: fish from a dry pond, flies
swarming on rotten meat, clear broth
clouding up with bacteria.
Redi’s Experiment
 1600’s
 He observed that wormlike maggots turned
into flies.
 He questioned spontaneous appearance on
meat.
 He set up a controlled experiment.
 He put meat in jars; some with netting on top
and some without netting.
 Flies only appeared on the uncovered meat.
Spallanzani’s Experiment
 Tested boiled broth that was sealed and
unsealed. Bacteria only grew on the
unsealed broth.
 Opponents believed that the air, which
was cut off from the broth, had “vital
force", so this did not persuade them.
Louis Pasteur
 Made a curve-necked flask that allowed
air to enter. The curve trapped particles
in the neck preventing them from
reaching the broth.
 The broth did not get cloudy.
 The spontaneous generation theory was
put to rest.
 Living things only come from other living
things.
Earth’s Beginnings
Earth began 4.6 billion years ago—very hostile
environment
-No oxygen in atmosphere
-Violent storms
↓
Anaerobic prokaryote cells inhabited the earth
-heterotrophs that lived in their own nutrients—
“primordial soup”
-no oxygen in atmosphere to be used for respiration
↓
Autotrophic anaerobic prokaryote cells
-cells evolved—now if you can make your own
food you are at an advantageno competition
for food
-Use CO2O2 produced
-Oxygen now in being released into the
environment
↓
Aerobic eukaryotes
-cells can now make more energy due to aerobic
respiration
↓ LONG PERIOD OF TIME
More complex organisms appear
If you compare the earth’s age to
the length of one day:
 12:00 midnight—earth created
 8:00 pm—life begins to evolve
 11:59 pm—mammals appear
What is Evolution?
 Evolution is the theory that species
change over millions of years because of
the changing environment.
Evidence of Change
1. Fossils – traces of once-living
organisms (EX: HARD PARTS like
shells, bones, teeth, and woody stems)
2. Found in SEDIMENTARY ROCKS. The
bottom layers are usually older.
3. Quick burial to avoid decay
Types of Fossils
A. ORIGINAL REMAINS have been found:
Mammoth, insects in amber, and frozen
humans.
B. Imprints form when the critter itself is
decayed, but a CARBON FILM remains.
C. A MOLD is a fossil impression of the
shape of a critter
D. A CAST forms when sediments fill in a
MOLD
Fossils can be DATED by testing for radioactive
decay
 C-14 DECAYS into N-14 losing a proton at a
constant rate.
 Use the HALF-LIFE to determine the age of a
fossil.
 The half-life of C-14 is about 5700 years.
– Only Useful up to 50,000 years.
– Use U-238 to find age of the oldest
rocks.
LIVING EVIDENCE
1. Homologous structures
 Come from the same part of the
EMBRYO, but have different functions
in different animals.
Ex: bones of alligator, human, penguin.
LIVING EVIDENCE
2. Vestigial Organs
 Organs or structures that are seemingly
functionless. They are often similar to
structures that are functional in other
organisms.
Ex: Human ear muscles, tailbone, and
appendix, pelvic and limb bones in
snakes, eyes in blind cave-dwelling
salamanders.
LIVING EVIDENCE
3. Biochemistry
 The same chemicals serve the same
function in vastly different organisms.
Ex: - Metabolism (digestion) is based
on the same biochemical compounds in
vastly different species.
– DNA can tell how closely related two
organisms are.
– CYTOCHROME C is in all AEROBES.
LIVING EVIDENCE
4. Embryological Development
 Embryos of different species develop
almost identically, especially in early
stages.
LIVING EVIDENCE
5. Analogous Structures
 Structures that serve similar functions
but differ in structure.
Ex: Fin on a dolphin and a fish. Wings
on a butterfly and a bird.
Evolutionary Scientist
Jean Lamarck
 1809
 "the inheritance of acquired
characteristics"
EX: Salamanders that did not use legs lost
them and began to slither. The next
generations would also have no legs or
small legs
Father of Evolution
Charles Darwin
 NATURALIST who took a Voyage on the Beagle
- (1831) in order to collect specimens and map
South America and the South Pacific.
 Observed that over time the land changed creating new HABITATS.
Ex: Earthquakes, old marine fossils in
mountains
 Animals would have to ADAPT to these
changes.
Charles Darwin
 He collected 13 different finch species, with
different types of beaks (bills). Darwin inferred
that they shared a common ancestor, but were
SPECIALIZED for different foods.
 He also collected fossils of extinct mammals that
were similar to modern mammals. This led him to
believe that species changed over time.
 In 1838, Darwin read Malthus’s Principles of
Populations, in which Thomas Malthus explained
the "struggle for existence" brought on by
competition for the Earth’s limited resources.
Charles Darwin's
THEORY OF EVOLUTION
 VARIATION exists among individuals of a
population.
 There exists a SCARCITY OF RESOURCES.
 Those better SUITED than the competition would
survive and REPRODUCE, while others dies off
due to NATURAL SELECTION.
 ADAPTATIONS which helped an individual to
survive could be INHERITED by the offspring.
 Alfred Russell Wallace came up with the same idea
in 1858 which convinced Darwin to publish
 Darwin published The Origin of Species in 1859.
 His book is now the unifying theme for all of Biology
EVOLUTIONARY PATTERNS
 The Galapagos finches most likely evolved from
one ancestor by ADAPTIVE RADIATION: from
common ancestor spreading into new HABITATS.
 DIVERGENT RADIATION is the process by which
two related species become more and more
dissimilar as they adapt to differing HABITATS.
-The Kit Fox’s sandy color helps it to hide in the
desert while the Red Fox’s color is good for
blending in with trees. The colors are adaptations.
EVOLUTIONARY PATTERNS
 CONVERGENT EVOLUTION occurs when two
separate species must both adapt to similar
environments.
EX: Plant leaves from the Sahara are similar to
those in Arizona.
 COEVOLUTION can be thought of as a sort of
“jockeying for position” between two species.
-Bees and the flowers they POLLINATE.
Survival Skills
 In order to continue the species,
reproduction must occur.
 Organisms that have beneficial
characteristics tend to survive and are
able to reproduce—passing on genes
Examples:
-Fast
-Strong
Survival Skills
In order to survive, organisms have
developed mechanisms which allow
them to trick predators.
1. Camouflage—blending in with the
environment to not be seen.
– Predator—to trick and catch prey
– Prey—blend so predator cannot see
Survival Skills
ExamplePeppered moths—white moth with
dark spots
 Tree bark light in color—advantageous to be
light with very few dark spots
 1900’s—industrial revolution occurs—pollution
created
 Due to pollution tree bark became darker
 Light moths stood out on dark bark—genes for
darker color became more beneficial
Survival Skills
2. Mimicry—acts or looks like another
organism
-Benefits prey—trick predator to think
organism is something it is not
ExampleButterfly with spots on wings
to look like eyes of larger animal