Download Darwin`s Theory of Evolution The Puzzle of Life`s Diversity Chapter

Theory of Evolution
WRITE A DEFINITION:
THEORY:
• a well-supported testable concept that is backed-up by
evidence
• Concept has been tested multiple times and is proven
EVOLUTION:
•
gradual change over time; the process by which
modern organisms have descended from ancient
organisms
Ideas that shaped Darwin’s thinking:
James Hutton (1795)the EARTH was shaped by geological
forces occurring over very
long periods of time, and the Earth is
millions of years old.
Ideas that shaped Darwin’s thinking:
Charles Lyell (1830)the geological processes still occurring now
have shaped Earth’s features over long periods
of time
http://www.biologydaily.com/biology/Sir_Charles_Lyell
Formation of Earth
• The Earth is about 4.8 billion years old
• According to science, the Earth was put
together piece by piece over the course of
about 100 million years
Early Earth Atmosphere
Earths early
atmosphere was
made up of 6 main
things:
• Hydrogen cyanide
• Carbon dioxide
• Carbon monoxide
• Nitrogen
• Hydrogen sulfide
• water
Could you have lived on
early Earth?
Cooling of the Earth
• Not only was the atmosphere not suitable
for life the early Earth was VERY hot
• About 4 billion years ago the earth began
to cool
– Rocks formed on the earths surface
Formation of water
• 3.8 billion years ago the earth cooled even
more
– Liquid was able to remain on the earths
surface forming the first oceans
video
Free Oxygen
• Fossils of prehistoric bacteria have been
found in rocks that are dated to be more
the 3.5 billion years old
• 2.2 b.y.a. Photosynthetic bacteria began
producing oxygen as a by product of
photosynthesis
Free Oxygen
• Free oxygen mixed with iron in the ocean
forming iron oxide
• Oxygen gas started accumulating in the
atmosphere, forming the ozone layer
• Increased oxygen levels
caused some life forms
to go extinct and allowed
other life forms to evolve
Ideas that shaped Darwin’s thinking:
Theory of PangaeaAll land was at one time
connected
Ideas that shaped Darwin’s thinking:
Continental driftshifting of the earths continent/ crust
divergent
convergent
Transform
Division of Life on Earth
• Life on Earth is
divided into Eras and
Periods
– Eras are bigger than
periods
• Based on fossil
evidence
– major changes that
occurred in the Earth’s
climate and geography
affected the living
organisms
Darwin’s Theory of Evolution
The Puzzle of Life’s Diversity
Chapter 15-1
Image from: Biology by Miller and Levine; Prentice Hall Publishing©2006
Charles DarwinThe person who contributed the
most to our understanding of
evolution
In 1831, he joined the crew of the Beagle as a
naturalist for a 5 year voyage around the world.
The Fossil Record
• Fossil record showed 2 types of organisms
– Ones that were similar to animals and plants alive
at the time
– Ones that were different to animals an plants
alive at the time
• Why had these
species disappeared?
– 99% of all species that have
ever lived on Earth are extinct
Fossils and Ancient Life
• What is a fossil?
– Hardened remains of plant or animal in rock
• Why do scientist use fossils?
• Fossils allow us to infer what past life
forms were like
– Structure
– Predator/Prey
– Habitat
How Fossils Form
• After the organism
dies the remains must
be preserved
• The dead organism is
buried by sediment
– Mud
– Sand
– dust
How Fossils Form
• Different types of fossils can be
formed
– Eggs
– Foot prints
– Bones
– Leaves
Relative Dating
• Most fossils form in
sedimentary rock
– formed by the deposition of
materials at the Earth’s
surface
• The age of a fossil is
determined by comparing
its placement with that of
fossils in other layers of
rock
– Layers of sedimentary rock
are built from oldest to
newest
Index Fossil
• Fossils used to define and identify
geological time
– When the organisms lived
• Species that existed for a short period of
time over a wide geographic range
Radioactive/Radiometric Dating
• Uses radioactive
elements to determine
how old the rock is
– Radioactive elements
decay at a steady rate
– The use of half-lives to
determine the age of a
To date older rocks you must
sample
use elements with longer half– Half life: the length of time
lives
required for half of the
Carbon-14 (5,730 years)
radioactive atoms to decay
Uranium (half-life: 4.47
b.y.)
How the fossil record is used
• used to show change
in organisms over
time
– Evidence of gradual
change
• life on earth is divided
based on changes in
the fossil record
– Transitions marked by
extinction
– Extinction makes new
habitats available to
species
DARWIN WONDERED?
Why do Argentina and Australia have different
Animals even though they have similar
grassland?
Why have so many species
disappeared?
How are these extinct species
related to living species?
Ideas that shaped Darwin’s thinking:
Jean-Baptiste Lamarck (1830)• one of first scientists to recognize
living things changed over time and that all
species were descended from other species.
Lamarck's Hypothesis:
1. Tendency towards perfection
2. Use and disuse
3. Inheritance of acquired traits
Tendency Towards Perfection
• Innate tendency toward
complexity and
perfection
• Organisms are
continuously changing
and acquiring traits that
benefit them
Use and Disuse
• By selective use or disuse of organs, organisms
acquire or loose traits during their life time
• These traits are passed down to offspring
The male fiddler crab uses its
front claw to attract mates and fight
off predators.
Through repeated use, the front claw
becomes larger.
The fiddler passes on this acquired
characteristic to its offspring
Inheritance of Acquired traits
• Acquired traits could be
passed on to offspring
– Lamarck didn’t know about
genes and how traits are
inherited.
If you lifted weights your
whole young adult life, and
then you had children, would
your kids be more
muscular?
Inheritance of Acquired traits
What’s wrong with Lamarck’s
hypotheses?
• Individuals DO NOT evolve
– You cannot change your DNA
• Acquired traits cannot be passed down to
offspring
• An organisms behavior has no effect on its
heritable characteristics
What’s right with Lamarck’s hypothesis?
Lamarck recognized
that organisms are
Adapted to their
environment
What does drive evolution?
• Evolution=
•Inherited adaption's
that accumulate in a
population over many
generations
competition
Darwin's greatest influence
Charles Darwin spent one month observing life on
the Galapagos Islands.
There, he encountered some unique animals, such
as finches and tortoises.
http://www.darwinadventure.com/pictures/galapagos_giantortoise.jpg
http://mikebaird.com/ecuador/images/galapagos_off_ecuador_ng_map.jpg
A summary of Darwin’s Theory
1. Individual organisms differ and some of the
variations are genetic
WHY DOES
VARIATION
MATTER?
The Galapagos Islands are close together but
have very different climates.
• hot and dry, with little vegetation
• more rainfall and were rich in vegetation
Each island had
its own unique
Assortment of
plant and animal
species.
Biology by Miller and Levine; Prentice Hall Publishing©2006
Inherited Variation
• Inherited variationpassed from parents to
offspring
How are traits passed
from parents to offspring
hint: think about meiosis
• Crossing over
• Random lining up of
chromosomes
A summary of Darwin’s Theory
2. Organisms produce more offspring then
can survive, and many that do survive do
not reproduce.
– High birth rates and a shortage of resources
force organisms into competition
Ideas that shaped Darwin’s thinking:
Thomas Malthus (1798)• If the human population continued to grow
unchecked, there would be insufficient living
space and food.
• Individuals adjust
to limited resources
Natural selection
• Each individual differs
from other members in its
species
– Each has unique
advantages and
disadvantages
• Natural selection- based
on their traits, some
individuals are able to
survive longer then others
– Takes place without human
control or direction
Organisms cannot change their
characteristics or force natural selection…
Giant Tortoises of the Galápagos Islands
Section 15-1
and on Pinta Island, tortoise necks
were somewhere in between
Pinta
Pinta Island
Tower
Marchena
Intermediate shell
Fernandina
James
Santa Cruz
Isabela
Santa Fe
Hood Island
Floreana
Isabela Island
Hood
Saddle-backed shell
On the desert-like Hood Island,
tortoises had long necks…
Dome-shaped shell
…while
Go to on the lush rainforest of Isabela Island,
Section:tortoises had short necks…
Natural Selection doesn’t give organisms what
they need to survive
Artificial Selection
• Artificial selection- nature provided the
variation and humans selected for the
variations they saw useful.
– Used to improve crops and livestock
(selective breeding)
A summary of Darwin’s Theory
3. Because more organisms are produced
then can survive, they compete for limited
recourses.
– Food
– Shelter
– Space
– Mates
The struggle for existence
• Competition what drives evolution
If there is no competition there is no evolution
A summary of Darwin’s Theory
4. Each organism has different advantages
and disadvantages in the struggle for
existence.
• Survival of the Fittestthe ability of an organism
to survive and reproduce
in its specific environment
Survival of the Fittest
• Fitness is a result of adaption's
– Adaptation= inherited characteristics that
increase an organisms chance of survival
Is the most fit
animal always the
biggest, strongest
and fastest?
Survival of the Fittest?
Adaptation vs. the ability to
adapt
• Adaptation- a trait or characteristic that
you re born with
• Ability to Adapt- How you use your traits or
characteristics to survive
Individuals DO NOT changes
• Individuals are unchanging
• Individuals either live or die based on the
traits that they inherited from their parents
A summary of Darwin’s Theory
5. Species alive today are
descended with
modifications from
ancestral species
Review of Darwin’s Theory
• Individual organisms differ and some of the
variations are genetic
• Organisms produce more offspring then can
survive, and many that do survive do not
reproduce.
• Because more organisms are produced then can
survive, they compete for limited recourses.
• Each organism has different advantages and
disadvantages in the struggle for existence.
• Species alive today are descended with
modifications from ancestral species
Review of Darwin’s theory
• Adaptations- an inherited trait or
characteristic that is passed down from on
generation to the next
– NOT something gained during your life time!
• Acquired traits- are not passed down
• The ability to adapt- how an organism is
able to use their adaptations to their
advantage in order to survive in their
environment
Conditions for natural selection
Conditions for natural selection include:
• Variations exist among members of a
population
• Many more individuals are produced each
generation than will survive
• Some individuals are better adapted so they
survive & reproduce
• Members of a population compete for food,
space, mates...
Evidence for Evolution
Fossil Record
Geographic Distribution
Homologous Body Structures
Similarities in Embryology
Fossil record
Fossil record
• The fossil record is a
history of life on Earth
– The earth is millions of
years old
• Which scientists
proposed this?
– Fossils that are found
in different rock layers
show the evolution of
living species over
millions of years
Fossil Record
• Transitional fossils-document various
intermediate stages in the evolution of
modern species
Incomplete Fossil Record
• Not all fossils have been found
– We are still finding new fossils
– The gaps in the fossil record are getting
smaller
• Not all organisms that ever live become
fossilized
– Soft bodied organisms are not fossilized
– Organisms that don’t die in or by the water
are usually not fossilized
Geographic distribution
• when a population gets
separated difference
selective pressures will
work on the
populations and cause
changes
• Divergent Evolutionpopulations evolve
separately
– Formation of new
species
Geographic distribution
• The environment
selects for specific
adaptations
– If the environment is the
same in 2 different
locations we see the
evolution of similar but
unrelated species
– Convergent evolutionevolution of shared traits
in unrelated species
• Bats and birds
Homologous body structures
Homologous
structures: variations
on a body structure
that was present in
their common
ancestor
Vestigial Structures
• structures or organs that
seem to serve no useful
function
– Human tail bone
– Whales tiny pelvic and
limb bones
– Ostriches wings
• vestigial structures show
common ancestry with
organisms in which the
homologous structure is
still functional.
Similarities in Embryology
• The early stages of
development are similar
in different species
– All animals with
backbones
• The same groups of
embryonic cells
develop in the same
order and pattern
– Cause for homologous
structures
Descent with modification
• Natural selection
produces organisms
that have different
characteristics
– Species today look
different then their
ancestors
• Common descent: All
living organisms are
related to one another
– A single tree of life links
all living organisms