Download Evolution - Pleasantville High School

The Origin
of Life
Biogenesis
 The idea that all living things come from
other living thing
 Spontaneous generation- living things
could come from non-living things
 Ex; flies coming from dead bodies
 Frogs/fish coming from rain
 Scientists did different experiments to
disprove this theory
Redi’s Experiment
 Francesco Redi was an
Italian doctor to first disprove
spontaneous generation.
 Redi put meat into three
different jars
 Jar 1 was left open
 Jar 2 was covered with
cloth
 Jar 3 was sealed closed
 What do you think
happened?
 Jar 1- maggots developed
and flies were observed
laying eggs on the meat.
 Jar 2- maggots developed on
the netting and flies were
observed laying eggs on the
netting.
 Jar 3- no maggots
developed.
 This proved that living things
could not generate from nonliving things.
Pasteur’s
Experiment
 Louis Pasteur was a French Chemist
and Microbiologists.
 It was believed that microorganisms
were in the air.
 Pasteur used boiled broth to show that
microorganisms can only generate from
other microorganisms in dust particles
 He also refuted the idea of spontaneous
generation.
Earth’s
History
Earth
 Earth was formed 4 ½ billion
years ago.
 How do we know this?
 Radioactive dating
 the rate of radioactive decay
of an isotope is known as an
elements half-life
 Half-life is the amount of time
it takes a radioactive isotope
to decay.
 Carbon -14 ~ about 6,000
years
 Uranium -238 ~ 4.5 million
years
First Life on Earth
 Oparin-Haldane Hypothesis
 Early Earth was composed


of: ammonia, carbon
dioxide methane,
hydrogen, and water vapor.
Primordial sea served as a
“chemical laboratory”
powered by solar energy.
The sea became a “hot,
dilute soup” containing
large populations of
organic molecules –
LIVING CELLS
The First Living Cells
 The first cells:
 Prokaryotic- one cell
 Anaerobic- “without air”
 Heterotrophic- relay on a carbon
source
 The competition for food created
autotrophs
 The CO2 created by heterotrophs and
O2 created by autotrophs changed the
atmosphere on Earth
Prokaryotic Cells
• No nucleus
• Most primitive, early
forms of life
• No membrane bound
organelles
Eukaryotic Cells
• True nucleus
• More complex
organisms
• Reproduce sexually
with the use of
meiosis.
Evidence
and Theory
of
Evolution
The Fossil
Record
Fossils

Direct or indirect remains of
organisms preserved in material
such as:




Relative Dating of Undisturbed
Sedimentary Rock and its Fossils
Sedimentary rocks
Amber
Ice
Tar

Single celled organisms date
back to 3 billion years ago.

About a billion years ago multicelled organisms began to
evolve.
Upper strata generally contain fossils of
younger, more complex organisms,
whereas, the lower strata contain fossils of
simpler life forms. This means there is a
tendency toward increasing complexity in
life forms over time.
The Law of Superposition
 Nicolaus Steno (1669)
 Younger strata will be deposited on-top
of older strata.
 The higher up you go in an undisturbed
rock layer, the younger the rock layers
become and therefore it is believed the
fossils within these layers, as compared
to lower rock layers.
 Common ancestors can be determined.
Evolution and
Natural
Selection
Diversity, Variation and
Evolution
 Living organisms are both similar
and varied.
 Organisms can be very
different (a flower and a tree;
human and a horse), yet they
share similarities.
 Every organism must have
some type of way of:
 Obtaining Energy
 Reproducing
 Exchanging substances with
the environment
Unity of Pattern
 There is a unity of pattern in
the structures and functions
of different organisms.
 Unit of pattern in DNA- only
one basic genetic code for all
organisms, including humans
 Can also be seen in the
structures of various
organisms.
 Vertebrates provide a good
example
Even the most diverse types of
vertebrates have relations.
Reproductive and
developmental processes
also have unit of pattern
All organisms are grouped
into species
Reproductive Isolation
Variations
 Organisms that are so closely
 Sometimes, organisms in the
 The inability of one group to
 Not all dogs look alike, but
similar that they can mate and
produce fertile offspring are
grouped in the same species.
interbreed successful with any
other group is reproductive
isolation,
 Polar bears and brown
bears have been
successfully mated in zoos,
but no such cross has been
found in the wild. Why not?
same species may not look
like one another.
they can interbreed
 Usually done easily, but
dogs such as a Great Dane
and a Yorkie will have
difficulty.
 Variations are differences
among individuals of a
species.
 Not all humans look the
same.
Darwin and the Galapagos
Islands
 In 1831 Charles Darwin
started his voyage on the
H.M.S. Beagle.
 He studied South America
and islands in the Pacific.
 The Galapagos Islands are
off of the coast of Ecuador.
 Darwin studies many forms
of life on these Islands, but
most famously finches and
tortoises.
 He continued to study these
organisms when he returned
to England.
Finches

Darwin was able to indentify 13
different species of finches,
primary by the size and shape of
their beaks.

Darwin surmised that these
finches must have originally
came from South America.

Darwin studied the work of
Reverend Thomas Malthus,
about human overpopulation.

Malthus stated that populations
tend to increase and if they
continue they would outstrip
their food supply.
Evolution and Natural
Selection

Artificial selection- breeders
could accentuate desirable traits
and characteristics by carefully
selecting animals for mating.

Darwin thought that there may
be a similar process that
occurred in nature.

He felt that organisms were
somehow selected by their
environment.

Individuals with desirable traits
were selected by their
environment.

Natural Selection- the process
by which those characteristics
that enhance survival and
reproduction are continued and
eventually replace less
advantageous characteristics.
Theory of Natural Selection
1.
Overproduction: within a population, more
offspring are born than could survive.
2.
Competition: Numbers of individuals tend
to remain constant and due to limited
resources there is a struggle for survival.
3.
Survival of the Fittest: The individuals
who survive are those who are best
adapted to their environment.
4.
Reproduction: Variations have an effect
on which organisms survive. Favorable
variations are passed on.
5.
Speciation: Adaptations are passed on
and new species may evolve from a
common ancestor.
Adaptations
The characteristics that enable
some members of a species or
population to survive and
reproduce more frequently
 Adaptations are part of the
variations in the population
 Darwin proposed that variations
appear randomly.
 If a variation was desirable,
then it will spread to future
generations.
Example of Natural Selection: The
Peppered Moth
 Two varieties of Peppered Moths existed;
light and dark ones.
 As industrialization increased in England,
where these moths lived, the environment
became dirtier.
 What do you think happened to these
moths?
Evidence of
Evolution
Structures
Homologous Structures
Analogous Structures

Body parts that are alike
because of a common ancestor


These structures may serve the
same or different functions

Ex. Forelimbs
Body parts that are similar in
structure and functions that have
no anatomical or embryological
similarities

Ex. Bird wings and insect
wings
Vestigial Organs
 Organs that were useful for an
ancestors, but no longer useful in the
modern day species.
 Ex. Appendix
 Jean Baptiste Lamarck discovered and
named vestigial structures
 Use and Disuse- Individuals lose
characteristics they do not require (or
use) and develop characteristics that
are useful.
Patterns of
Evolution
Co-evolution
• A change of two or
more species in close
association with each
other
Convergent
Evolution
• Organisms in the
same environment
adapt in a similar
manner
Divergent
Evolution
• Two related species
become more and
more different in
response to different
environments