evolution (1).ppt

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.

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

Struggle For Existence &
Survival of The Fittest

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
appear different, yet have common origin.
This indicates similar DNA and ancestral
origin

Evidence for Evolution
 Vestigial organs-organs that serve
no useful function in an organism
 i.e.) appendix, wisdom teeth in
humans, tailbone. Pelvic bone in
whale

Analogous structures
 Structures that APPEAR similar and have
similar functions, but the internal structure
is very different. These organisms DO NOT
share a common ancestor.
 (i.e., Bat wing and the
butterfly wing)

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

Conditions of Early earth
 Atmosphere composed of
Carbon Dioxide, Nitrogen,
Water, Ammonia. Very
little Oxygen.
 No plant or animal life
 Volcanic eruptions
 Many organic compounds
(especially amino acids)
 High temperatures 200
degrees Celcius

Miller-Urey Experiment
 Was an experiment that re-
created the conditions of
early earth
 They were trying to see
which substances existed in
early earth
 They suggested that
primitive earth had an
abundance of organic
compounds (lipids, proteins,
nucleic acids, and
carbohydrates)

Endosymbiotic Theory
 http://biology.kenyon.edu/HHMI/Biol113/the%20e
ndosymbiotic%20theory.htm
 States that chloroplasts and mitochondria are the
two organelles who have their own DNA
independent of the rest of the cell.
 The theory states that one ancient bacteria engulfed
(ate) the other, and created these organelles

Antibiotic Resistance/Pesticide
Resistance
 During the course of many years, certain bacteria have evolved
and developed resistance to antibiotics (favorable inherited
mutation)
 This is beneficial to the bacteria, and harmful to the organism
infected.
 MRSA-antibiotic resistant illness.
 This was a helpful mutation to the bacteria. These traits were
passed on to future bacteria that made them stronger (Natural
Selection)
 Plants who had the mutation to survive pesticides passed this
trait on to other plants. These plants survived, and reproduced—
making more plants that were resistant to pesticides

evolution (1).ppt

More Related Content

Similar to evolution (1).ppt

Recently uploaded

evolution (1).ppt