1 Charles Darwin The Naturalist. 2 Charles Darwin Born Feb. 12, 1809 Born Feb. 12, 1809 Joined Crew...
43
1 Charles Darwin The Naturalist
1 Charles Darwin The Naturalist. 2 Charles Darwin Born Feb. 12, 1809 Born Feb. 12, 1809 Joined Crew of HMS Beagle, 1831 Joined Crew of HMS Beagle, 1831
2 Charles Darwin Born Feb. 12, 1809 Born Feb. 12, 1809 Joined
Crew of HMS Beagle, 1831 Joined Crew of HMS Beagle, 1831 Naturalist
Naturalist 5 year voyage around world 5 year voyage around world
Avid collector of flora (plants) & fauna (animals) Avid
collector of flora (plants) & fauna (animals) Astounded by
variety of life Astounded by variety of life
Slide 3
3 A reconstruction of the HMS Beagle sailing off. Darwins
Voyage of Discovery
Slide 4
4 Darwin Left England in 1831 Darwin returned 5 years later in
1836
Slide 5
5 The Galapagos Islands Small chain of islands off the coast of
Ecuador in South America Small chain of islands off the coast of
Ecuador in South America Very different climates Very different
climates Animals on the islands were unique Animals on the islands
were unique Tortoises Iguanas Finches
Slide 6
6 The Galapagos Islands Darwin noted that the species found on
one island looked different from those on nearby islands Darwin
noted that the species found on one island looked different from
those on nearby islands Many of the islands species looked
different than mainland species Many of the islands species looked
different than mainland species
Slide 7
7
Slide 8
8 The Galapagos Islands Finches on the islands resembled a
mainland finch Finches on the islands resembled a mainland finch
Different types of finches appeared on the islands where the
available food was different (seeds, nuts, berries, insects, etc.)
Different types of finches appeared on the islands where the
available food was different (seeds, nuts, berries, insects, etc.)
Finches had different types of beaks adapted to their type of food
gathering Finches had different types of beaks adapted to their
type of food gathering
Slide 9
9
Slide 10
10 Darwins Observations & Conclusions The Struggle for
Existence
Slide 11
11 Voyage of the HMS Beagle During his travels, Darwin made
numerous observations and collected evidence that led him to
propose a revolutionary hypothesis about the way life changes over
time
Slide 12
12 Darwins Observations Patterns of diversity were shown
Patterns of diversity were shown Unique adaptations in organisms
Unique adaptations in organisms Species not evenly distributed
Species not evenly distributed Australia had kangaroos, but no
rabbits S. America the only continent with Llamas
Slide 13
13 Darwins Observations Both living organisms & fossils
collected Both living organisms & fossils collected Fossils
included: Fossils included: Trilobites Giant Ground Sloth of South
America This species NO longer existed. What had happened to
them?
Slide 14
14 Evidence for Evolution The Fossil Record
Slide 15
15 Evolution The slow, gradual change in a species over
time
Slide 16
16 Darwins Observations Left unchecked, the number of organisms
of each species will increase exponentially, generation to
generation In nature, populations tend to remain stable in size
This is because environmental resources are limited
Slide 17
17 Darwins Conclusion Production of more individuals than can
be supported by the environment leads to a struggle for existence
among individuals Only a fraction of offspring survive each
generation Survival of the Fittest
Slide 18
18 Darwins Observations Individuals of a population vary
extensively in their characteristics with no two individuals being
exactly alike. Much of this variation between individuals is
inheritable.
Slide 19
19 Darwins Conclusion Individuals who inherit characteristics
most fit for their environment are likely to leave more offspring
than less fit individuals Called Natural Selection
Slide 20
20 The unequal ability of individuals to survive and reproduce
leads to a gradual change in a population, with favorable
characteristics accumulating over generations (natural
selection)The unequal ability of individuals to survive and
reproduce leads to a gradual change in a population, with favorable
characteristics accumulating over generations (natural selection)
New species evolveNew species evolve Darwins Theory of
Evolution
Slide 21
21 Darwins Theory of Evolution Organisms Change Over Time
Slide 22
22 Common Descent with Modification Darwin proposed that
organisms descended from common ancestors Darwin proposed that
organisms descended from common ancestors Idea that organisms
change with time, diverging from a common form/ancestor Idea that
organisms change with time, diverging from a common form/ancestor
Caused evolution of new species Caused evolution of new
species
Slide 23
23 Natural Selection Driving force for evolution Driving force
for evolution During the struggle for resources, only the strongest
survive & reproduce During the struggle for resources, only the
strongest survive & reproduce Characteristics which impact
organisms survival and fertility are inheritable Characteristics
which impact organisms survival and fertility are inheritable
Slide 24
24 Origin of Species Darwin Presents His Case
Slide 25
25 Publication of On The Origin of Species Upon his return to
England, Darwin developed his observations into The Theory of
Evolution Upon his return to England, Darwin developed his
observations into The Theory of Evolution But he did not publish
for 25 years!! But he did not publish for 25 years!!Why???
Slide 26
26 Publication of On The Origin of Species Darwin knew that his
theory would be extremely controversial and would be attacked
Darwin knew that his theory would be extremely controversial and
would be attacked His theory challenged established religious &
scientific beliefs, particularly about the creation of man His
theory challenged established religious & scientific beliefs,
particularly about the creation of man
Slide 27
27 Publication of On The Origin of Species He refused to
publish until he received an essay from Alfred Wallace He refused
to publish until he received an essay from Alfred Wallace Fellow
Naturalist Independently developed the same theory of evolution,
that species changed over time because of their struggle for
existence When Darwin read Wallaces essay, he knew he had to
publish his findings
Slide 28
28 Natural Variation and Artificial Selection Natural Variation
Natural Variation Differences among individuals of a species
Artificial Selection Artificial Selection Selective breeding to
enhance desired traits among stock or crops
Slide 29
29 Natural Variation and Artificial Selection Key Concept: In
Artificial Selection, nature provided the variation among different
organisms, and humans selected those variations that they found
useful
Slide 30
30copyright cmassengale
Slide 31
31 Origin of Species Concepts and Controversy
Slide 32
32 Evolution By Natural Selection Concepts The Struggle for
Existence: compete for food, mates, space, water, etc. The Struggle
for Existence: compete for food, mates, space, water, etc. Survival
of the Fittest: strongest are able to survive and reproduce
Survival of the Fittest: strongest are able to survive and
reproduce Descent with Modification: new species arise from common
ancestor, replacing less fit species Descent with Modification: new
species arise from common ancestor, replacing less fit species
Slide 33
33 Survival of the Fittest Fitness Ability of an individual to
survive & reproduce Adaptation Inherited characteristic that
increases an organisms chance for survival
Slide 34
34 Survival of the Fittest Adaptations can be: Physical Speed,
Camouflage, Claws, Quills, etc. Behavioral Solitary, Herds, Packs,
Activity, etc.
Slide 35
35 Survival of the Fittest is central to the process of
evolution Fitness is central to the process of evolution
Individuals with low fitness Individuals with low fitness die
produce few offspring Survival of the Fittest!! AKA AKA Natural
Selection!!
Slide 36
36 Survival of the Fittest Key Concept Over time, Natural
Selection results in changes in the inherited characteristics of a
population. These changes increase a species fitness in its
environment.
Slide 37
37 Natural Selection Cannot Be Seen Directly Cannot Be Seen
Directly It Can Only Be Observed As Changes In A Population Over
Many Successive Generations It Can Only Be Observed As Changes In A
Population Over Many Successive Generations Radiation Fossil
Record
Slide 38
38 Descent With Modification Takes place over long periods of
time Takes place over long periods of time Natural Selection can be
observed as changes in: Natural Selection can be observed as
changes in: Body Structures Ecological Niches Habitats
Behaviors
Slide 39
39 Descent With Modification Species today look different from
their ancestors Species today look different from their ancestors
Each living species has descended with changes from other species
over time Each living species has descended with changes from other
species over time
Slide 40
40 Descent With Modification copyright cmassengale
Slide 41
41 Descent With Modification Implies Implies All living
organisms are related We all fit onto a single Tree of Life DNA,
Body Structures, Energy Sources Common Descent All species, living
& extinct, were derived from common ancestors
Slide 42
42. Major Problem in Darwins Theory No mechanism to explain
natural selection How could favorable variations be transmitted to
later generations? With the rediscovery of Mendels work in the
first half of the 20th century, the missing link in evolutionary
theory was found
Slide 43
43 Opposition to Evolution The upheaval surrounding evolution
began with Darwins publication of On the Origin of Species By Means
of Natural Selection The debate continues nearly 150 years
later