Download The Evidence 1) Perpetual change

Chapter 4 & 5
• Organic Evolution
Before Darwin
Jean Baptiste Lamarck
• Lamarckism:
inheritance of
acquired
characteristics
• Transformational
view of evolution
• Not supported.
1744-1829
Sir Charles Lyell
• Uniformitarianism
• Laws of physics and
chemistry remain the
same
• Natural processes
which acted in the
past will continue to
act.
1797-1875
Thomas Malthus
• Concerned with
human population
growth
• People tended to
reproduce faster
than their food
supply, and are
forced to compete for
existence.
1766-1834
Charles Darwin
• Naturalist who
combined the ideas
of Malthus, Lyell and
others to form the
theory of evolution.
1809-1882
DARWIN’S THEORY OF EVOLUTION
• A sea voyage helped Darwin frame his
theory of evolution
– On his visit to the Galápagos Islands
Charles Darwin observed many unique
organisms
– Darwin’s main ideas can be traced back to
the ancient Greeks
– Aristotle and the Judeo-Christian culture
believed that species are fixed
– In the century prior to Darwin the study of
fossils suggested that life forms change
– Geologists proposed that a very old Earth is
changed by gradual processes
– While on the voyage of the HMS Beagle in the
1830s Charles Darwin observed similarities
between living and fossil organisms and the
diversity of life on the Galápagos Islands
North
America
Great
Britain
Europe
Asia
ATLANTIC
OCEAN
PACIFIC
OCEAN
Africa
PACIFIC
OCEAN
Equator
The
Galápagos
Islands
PACIFIC
OCEAN
Pinta
South
America
Genovesa
Equator
Santiago
Pinzón
Fernandina
Isabela
0
0
40 km
Daphne
Islands
Cape of
Good Hope
Tasmania
Santa Santa
Cruz Fe
Florenza
40 miles
Australia
Andes
Marchena
Cape Horn
San
Cristobal
Española
Tierra del Fuego
New
Zealand
– Darwin’s experiences during the voyage of
the Beagle helped him frame his ideas on
evolution
Evolution
Evolution
• Change over time: Organic or biological
evolution is a series of changes in the
genetic composition of a population over
time.
Adaptation
Adaptation
• Occurs when a heritable change in a
phenotype increases an animal’s chance
of successful reproduction.
Adaptation
• Occurs when a heritable change in a phenotype
increases an animal’s chance of successful
reproduction.
• Likely to be expressed when an organism
encounters a new environment.
Adaptation
• Occurs when a heritable change in a phenotype
increases an animal’s chance of successful
reproduction.
• Likely to be expressed when an organism
encounters a new environment.
• Not every characteristic is an adaptation
to some kind of environmetal situation.
Adaptation
• Occurs when a heritable change in a phenotype
increases an animal’s chance of successful
reproduction.
• Likely to be expressed when an organism encounters a
new environment.
• Not every characteristic is an adaptation to some kind
of environmetal situation.
• A No No: evolutionary adaptations lead
to perfection.
Darwinian Evolutionary Theory:
The Evidence
1) Perpetual change
2) Common descent
3) Multiplication of species
4) Gradualism
5) Natural selection
I. Perpetual Change
• Darwin noticed fossils of extinct marine
organisms thousands of feet above present day
sea level.
The Burgess Shale
Before the Scientific Method
• People based their beliefs on their
interpretations of what they saw
– Without testing their ideas
• Rather, their conclusions were based on
untested observations.
Snakestones!
• Some fossils you can not refute.
The Baltic amber deposits range between 35 to 40
million years old and is the largest source of amber
yet discovered.
So What do these Fossils tell us?
Geological Time
• Long before the earth’s age was known,
geologists divided its history into a table
of succeeding events based on the
ordered layers of sedimentary rock.
– The fossil record reveals that organisms
have evolved in a historical sequence
Evolutionary trends
• The fossil record allowed Darwin to view
evolutionary change across the broadest
scale of time.
• Animal species typically survive
approximately 1 million to 10 million
years, before going extinct.
I. Perpetual Change
• Darwin noticed fossils of extinct marine organisms
thousands of feet above present day sea level.
• Darwin also worked on the change of animals
under domestication by humans (artificial
selection).
– Darwin found convincing evidence for his
ideas in the results of artificial selection
•
The selective breeding of domesticated
animals
I. Perpetual Change
• Darwin noticed fossils of extinct marine organisms
thousands of feet above present day sea level.
• Darwin also worked on the change of animals under
domestication by humans (artificial selection).
• He combined these two observations to form
the idea that organisms are constantly
changing through time.
II. Common Descent
• Whereas Lamarck believed in multiple
origins of life, Darwin believed that all
life originated from a single common
ancestor.
– Darwin proposed that living species are
descended from earlier life forms
African wild dog
Coyote
Wolf
Thousands to
millions of years
of natural selection
Ancestral canine
Fox
Jackal
Hi There How are You!!!
6-11, p 110
• How many species of horses are there?
Burchell's Zebra (Equus burchelli)
Mountain Zebra (Equus zebra)
Grevy's Zebra (Equus grevyi)
• Asiatic Wild Asses
- Kulan and Onager (Equus hemionus)
- Kiang (Equus kiang)
• African Wild Asses
- African Wild Ass (Equus asinus)
Przewalski's Horse (Equus caballus)
So what do these horse fossils
suggest?
• Throughout the history of all forms of
life, evolutionary processes generate new
characteristics that are then inherited by
subsequent generations.
II. Common Descent
• Whereas Lamarck believed in multiple origins of life,
Darwin believed that all life originated from a single
common ancestor.
• The evidence Darwin used was
homology:
Homologies
• Homologies: Anatomical structures
within different organisms which
originated from a structure or trait of
their common ancestral organism.
Vestigial Structures
What are these animals?
Analogous Structures
• The evolution of superficially similar
structures in unrelated organisms is
called convergent evolution.
So What?
Theory of Common Descent is
Testable
• Like all good scientific theories, common
descent makes several important predictions
that can be tested and potentially used to reject
it.
• According to this theory, we should be able to
trace the genealogies of all modern species
backward until they converge on ancestral
lineages shared with other species, both living
and extinct.