evolution doctrine.pptx

Darwin’s Theory of Evolution
 Evolution, or change over time, is the
process by which modern organisms have
descended from ancient organisms.
 A scientific theory is a well-supported
testable explanation of phenomena that have
occurred in the natural world.

How do you think Darwin came
up with his theory?

Voyage of Beagle
 Dates: February 12th, 1831
 Captain: Charles Darwin
 Ship: H.M.S. Beagle
 Destination: Voyage around the world.
 Findings: evidence to propose a
revolutionary hypothesis about how life
changes over time

Patterns of Diversity
 Darwin visited Argentina and Australia which had
similar grassland ecosystems.
 those grasslands were inhabited by very different
animals.
 neither Argentina nor Australia was home to the
sorts of animals that lived in European grasslands.

Patterns of Diversity
 Darwin posed challenging questions.
 Why were there no rabbits in Australia, despite the
presence of habitats that seemed perfect for them?
 Why were there no kangaroos in England?

Living Organisms and Fossils
 Darwin collected the preserved remains of
ancient organisms, called fossils.
 Some of those fossils resembled organisms that
were still alive today.

Living Organisms and Fossils
 Others looked completely unlike any creature he had
ever seen.
 As Darwin studied fossils, new questions arose.
 Why had so many of these species disappeared?
 How were they related to living species?

The Galapagos Island
 The smallest, lowest islands were hot,
dry, and nearly barren-Hood Island-sparse
vegetation
 The higher islands had greater rainfall and
a different assortment of plants and
animals-Isabela- Island had rich
vegetation.

The Galapagos Island
 Darwin was fascinated in particular by the land
tortoises and marine iguanas in the Galápagos.
 Giant tortoises varied in predictable ways from
one island to another.
 The shape of a tortoise's shell could be used to
identify which island a particular tortoise
inhabited.

Animals found in the Galapagos
 Land Tortoises
 Darwin Finches
 Blue-Footed Booby
 Marine Iguanas

The Journey Home
 Darwin Observed that characteristics
of many plants and animals vary
greatly among the islands
 Hypothesis: Separate species may
have arose from an original ancestor

Ideas that shaped Darwin’s
Thinking
 James Hutton:
 1795 Theory of
Geological change
 Forces change
earth’s surface
shape
 Changes are slow
 Earth much older
than thousands of
years

Ideas that Shaped Darwin’s
Thinking
 Charles Lyell
 Book: Principles of
Geography
 Geographical features
can be built up or torn
down
 Darwin thought if
earth changed over
time, what about life?

Lamarck’s Theory of Evolution
 Tendency toward Perfection(Giraffe
necks)
 Use and Disuse (bird’s using forearms)
 Inheritance of Acquired Traits

Population Growth
 Thomas Malthus-
19th century English
economist
 If population grew
(more Babies born
than die)
 Insufficient living
space
 Food runs out
 Darwin applied this
theory to animals

Publication of Orgin of Species
 Russel Wallace wrote
an essay summarizing
evolutionary change
from his field work in
Malaysia
 Gave Darwin the drive
to publish his findings

Natural Selection & Artificial
Selection
 Natural variation--differences among
individuals of a species
 Artificial selection- nature provides the
variation among different organisms, and
humans select those variations they find
useful.

Evolution by Natural Selection
 The Struggle for Existence-members of
each species have to compete for food,
shelter, other life necessities
 Survival of the Fittest-Some individuals
better suited for the environment

Natural Selection
 Over time, natural
selection results in
changes in inherited
characteristics of a
population. These
changes increase a
species fitness in its
environment

Descent
 Descent with Modification-Each living organism has
descended, with changes from other species over time
 Common Descent- were derived from common ancestors

Evidence of Evolution
 The Fossil Record
 Geographic Distribution of Living Things
 Homologous Body Structures
 Similarities in Early Development

Evidence for Evolution
 The Fossil Record-
Layer show change
 Geographic
Distribution of Living
Things
 Homologous Body
Structures
 Similarities in Early
Development

Evidence of Evolution
 The Fossil Record
 Geographic
Distribution of
Living Things-similar
environments have
similar types of
organisms
 Homologous Body
Structures
 Similarities in Early
Development

Homologous Structures
 Homologous Structures-structures that
have different mature forms in different
organisms, but develop from the same
embryonic tissue

Evidence for Evolution
 Vestigial organs-organs that serve
no useful function in an organism
 i.e.) appendix, miniature legs, arms

Similarities in Early
Development

Summary of Darwin’s Theory
 Individuals in nature differ from one
another
 Organisms in nature produce more offspring
than can survive, and many of those who do
not survive do not reproduce.

Summary of Darwin’s Theory
 Because more organisms are produce than
can survive, each species must struggle for
resources
 Each organism is unique, each has
advantages and disadvantages in the
struggle for existence

Summary (cont.)
 Individuals best suited for the environment
survive and reproduce most successful
 Species change over time

Summary (cont.)
 Species alive today descended with modification
from species that lived in the past
 All organisms on earth are united into a single
family tree of life by common descent

evolution doctrine.pptx

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