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Evolution
CHANGE OVER TIME
Evolution
 Refers to the process through which species
change over time
 This change results from a change in the genetic
material of an organism and is passed from one
generation to another
Influential Scientists
JEAN BAPTISTE DE LAMARCK
C H A R L E S DA RW IN
Jean Baptiste de Lamarck
(1744-1829)
 Believed
that the fossil record showed that the
species had changed over time
 Around
1800, he proposed that an organism could
ACQUIRE a new trait during its lifetime and then
pass that trait on to its offspring
 Unfortunately
he was unable to provide evidence
to support this theory
Jean Baptiste de Lamarck

Inheritance of Acquired Characteristics
Charles Darwin
(1809 - 1882)
W H O WA S C H A R L E S D A R W I N ?
H T T P : / / W W W. Y O U T U B E . C O M / WAT C H ? V = W V 9 O L U E R
YM0
Schooling
 Shrewsbury Grammar School
 Studied medicine at Christ's College, Cambridge
University

Witnessed surgery on a child…quit medicine
 Edinburgh
 Studies botany with Professor Henslow
 Wants to become a clergyman/naturalist like Henslow
The Voyage
 Reverend John Henslow and George Peacock invite
him to be the Naturalist aboard the H.M.S. Beagle
 Would survey South America
Charles Darwin
 After
the trip, he came up with the modern theory
of evolution, using his research from the 18
different Galapagos Islands
 He
found that plants and animals not only differed
from those he saw on the mainland, but some
differed from island to island
On The Origin of Species
 Collected massive amounts of data
while on his trip

(3 volumes of 1,000 pages a piece)
 Did not publish his book for 20
years

For fear of how people would react
Answer the following question
 Why is Charles Darwin important?

Restate the question in your answer.
Darwin’s Tortoises
Darwin’s Tortoises
 Tortoises:
 Darwin noticed that tortoises with short necks were living in
damp areas with abundant plant life that grew close to the
ground.
 Longer necked tortoises were living in dry areas with cacti.
 He considered whether the lengths of their necks made it
possible for the tortoises to live in different environments.
Darwin’s Finches
Darwin’s Finches

Among the different islands he
noticed a variety of beak shapes and
sizes.

Some finches had heavy, short beaks
useful for pecking trees or seeds,
while others had small, thin beaks
that could be used for capturing
insects.

These observations cause Darwin to
wonder if the birds had evolved from
similar species.
Bird's Beaks
How did tortoises and birds differ among the islands of the
Galapagos?
• competitive exclusion = adaptation = speciation
 Each island
had its own
type of
tortoises
and birds
that were
clearly
different
from other
islands
SPECIATION
The Formation of A New Species:
 portion of gene pool becomes isolated; process of
generating new species
 the accumulation of changes may separate a
population into distinct groups
Speciation
These squirrels live on opposite sides of the Grand Canyon.
This is an example of geographic speciation.
Speciation in Darwin’s Finches
 Speciation in the Galapagos occurred by:
- Geographic Isolation
which led to
- Reproductive Isolation
and
- Changes in the gene pool
driven by
- Competition.
Natural Selection
Natural Selection
 Natural Selection: This is a process by which
members of a species that are best suited to their
environment survive and reproduce at a higher rate
than other members of species
 “Survival of the fittest.”
Natural Selection
 Darwin came up with this theory of Natural Selection
based on 4 key principles:
1.
2.
3.
4.
overproduction
variation
adaptation
selection
Principles of
Natural Selection
 Overproduction:
 When a plant or animal
reproduces, it usually
makes more offspring than
the environment can
support
Principles of
Natural Selection
 Variation:
 Within a species there are natural differences in traits
among individuals
Principles of Natural Selection
Mutation:
• a change in genetic material causing a new variation to
come about which can be passed to the next generation
BrainPOP - Genetic Mutations
Principles of
Natural Selection
 Adaptation:
 any inherited trait that gives an organism an
advantage in its particular environment
Principles of
Natural Selection
 Selection:
 Individual organisms with a particular adaptation that
are most likely to survive long enough to reproduce
will pass this adaptation to the next generation.

As this process repeats from generation to generation, more
members of a species show the adaptation; the species is
evolving over time
Artificial Selection
 Outside forces guiding
selection of desired traits.
 Nature provides variation
then humans select upon
specific variations.
 Ex: A farmer breeds only
his best livestock
Evidence Supporting the Theory of Evolution
 Theory:
 A widely accepted statement based on scientific
evidence that helps explain a group of facts
Evidence Supporting the Theory
of Evolution
1.
B I O LO G I C A L E VO LU T I O N
Genetic Evidence
2.
G EO LO G I C A L E VO LU T I O N
Fossil Record
Evidence Supporting the Theory of Evolution
 Biological (Organic)Evolution:
 genetic change in a population of organisms

the change over time in the proportion of
individual organisms differing in one or more inherited traits
Biological Evidence
 Similarities in Structure:
 Vestigial Structures:
 physical structures that were
fully developed and functional in
an ancestral group of organisms
but are reduced and unused in
the later species.

Ex: Snakes have traces of leg-like
structures, whales also have
small leg-like structures that are
not used
Biological Evidence
 Similar

Structure, Different Function:
Many species share similar structures but the structures have
different functions

Ex: lizards, bats, and manatees have forelimbs that have a similar
bone structure but they are all used in different ways
Biological Evidence
Biological Evidence
 Similarities in Development
 Various animals look similar in their earliest stages of life
Biological Evidence
Genetic Evidence
 DNA is the genetic material found in all organisms
 DNA contains the information all organisms need to
grow and to maintain themselves
 When an organism reproduces they pass their DNA on
to their offspring
Genetic Evidence

Scientists are able to tell how closely organisms are related by
comparing their DNA