Notes

DARWIN’S
EPIC
JOURNEY
Born in 1809, Charles
Darwin longed to see the
world.
In 1831, he was invited to
take a trip on the HMS
Beagle, which is where he
came up with the theory of
Evolution
Evolution- the change in a
species overtime- organisms
descended from other
organisms
DARWIN’S
EPIC
JOURNEY
Darwin developed a
theory of biological
evolution that offered a
scientific explanation for
the unity and diversity of
life, by proposing how
modern organisms
evolved through descent
from common ancestors
(descent with modification)
OBSERVATIONS
FROM THE VOYAGE
Darwin saw that
species such as
beetles were so well
suited to their
environment, and
he wanted to know
why
He focused on
three patterns of
diversity:
Species vary globally
Species vary locally
Species vary over
time
SPECIES VARY GLOBALLY
Darwin also noticed flightless birds
The rhea only lived in South America
The ostrich only lived in Africa
The emu only lived in Australia
SPECIES VARY
LOCALLY
Darwin noticed that different,
yet related species often
occupied different habitats in the
same area
He saw this in the land tortoises
and the Galapagos finches
SPECIES
VARY
OVER TIME
Darwin also collected
fossils- preserved
remains of ancient
organisms
Darwin noted that the
fossil record included
many extinct animals
that were similar to
animals that were
living today.
PUTTING THE
PUZZLE TOGETHER
Darwin then went
back to London, and
began analyzing his
results.
It was now that he
saw that all the
birds that he found
were all species of
finch
Between this and the
other specimens, he
came up with the
theory of evolution
IDEAS THAT
INFLUENCED
DARWIN
Chapter 17 Section 2
Pallavi Rallapalli
AN ANCIENT,
CHANGING
EARTH
Hutton and Lyell
concluded that the Earth
is extremely old, and that
the processes that
changed Earth in the past
are the same processes
that operate in the
present.
HUTTON AND
GEOLOGICAL
CHANGE
Hutton recognized that the
connections between
geological processes and
features, like mountains,
valleys, and layers of rock
seem to be bent or folded
He concluded that over long
periods of time, we could
build mountain ranges
He knew that this took time,
and called it deep time
LYELL’S
PRINCIPLE
S OF
GEOLOGYUniformitarianism- says that
the geological processes
that we observe in the
present, are the same ones
that were present millions of
years ago
This allowed Darwin to
conclude that geological
events such as volcanos or
earthquakes, can push rocks
up, and shape the Earth’s
surface
LAMARCK’S
EVOLUTIONARY
HYPOTHESIS
Lamarck suggested
that individual
organisms could
change during their
lifetimes by
selectively using or
not using various
parts of their bodies.
He also suggested
that individuals could
pass these acquired
traits on to their
offspring, enabling
species to change
over time.
LAMARCK’S IDEAS
He proposed that all
organisms have an inborn
urge to become more
complex and perfect- so if
a parent acquired a
characteristic, they could
pass it on to their
offspring
EVALUATING
LAMARCK’S
HYPOTHESIS
Today we know that
the idea is not
supported
Acquired traits cannot
be passed on through
generations
Lamarck was the first
naturalist to suggest
that species are NOT
fixed
POPULATION
GROWTH
Malthus reasoned that
if the human population
grew unchecked, there
wouldn’t be enough
living space and food
for everyone.
 Suggested that the only
way to control population
growth was through war,
famine, and disease
This influenced Darwin
because if this idea
applied to people, it
applied to other
organisms as well.
ARTIFICIAL
SELECTION
Artificial Selection-
selective breeding of
plants and animals to
promote the occurrence of
desirable traits in the
offspring
In artificial selection,
nature provides the
inherited variations, and
humans select those
variants they find useful.ARTIFICIAL
SELECTION
Artificial Selection-
selective breeding of
plants and animals to
promote the occurrence of
desirable traits in the
offspring
In artificial selection,
nature provides the
inherited variations, and
humans select those

Darwin’s Theory:
Natural Selection
Chapter 17 Section 3
Pallavi Rallapalli
Evolution by
Natural
Selection  Described a natural process with a scientific
explanation
 Descent with Modification- all organisms have
a common ancestor
The Struggle for
Existence
 All populations have the potential to
produce many offspring but compete for
a finite amount of environmental
resources.
Variation and
Adaptation
 Individuals with certain
variations are better adapted
to their environment
 Adaptation- a heritable
characteristic that increases
an organism’s ability to
survive and reproduce in an
environment
Survival of the Fittest
 Adaptations affect an organism’s fitness
 Fitness- how well an organism can survive and
reproduce in its environment
 In evolutionary terms- survival means more
than just staying alive, it involves how many
offspring are left behind, and how if they
reproduce.
Natural Selection
 Natural Selection- process by which organisms that are
the most suited to their environment survive and
reproduce most successfully; aka: survival of the fittest
 Natural selection occurs in any situation in which more
individuals are born than can survive (the struggle for
existence), natural heritable variation affects the ability
to survive and reproduce (variation and adaptation),
and fitness varies among individuals (differential
reproductive success).
Common
Ancestry
 Natural Selection depends on an individual’s ability to reproduce and
leave descendants
 Well adapted individuals survive and reproduce- small changes
develop over time- descent with modification
 According to the principle of common descent, all species- living and
extinct- are united by descent from ancient common ancestors, and
exhibit diversity due to natural selection and adaptation