Download Evolution reading p49

HMS Beagle (1831-1836)
“Origins of Species by Means of
Natural Selection”
Organisms reproduce others of their own kind
 Overproduction of offspring
 Variations among offspring exist & some are
inherited
 Organisms with “favoured” variations
(adaptations) are more likely to survive & pass on
these adaptations to their offspring
 Nature selects the “fittest” organisms to survive &
reproduce
 Overtime, the survivors with the favorable
characteristics will make up most of the population
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Essential for a species to change over time
Some variations help an organism to survive
better within its environment
If an organism is able to survive, it will
reproduce, which enables offspring & further
generations to inherit these variations
A variation (characteristic or trait) that allows
an organism to survive & successfully
reproduce is an Adaptation.
 Over time, the survivors with the
favorable adaptations will make
up most of the population
 Plant and animal breeders
 Artificial breeding
 Variations within corn and milk
 Selection made of the best
Cabbage
Selection for
apical (tip) bud
Brussels
sprouts Selection for
axillary (side)
buds
Broccoli
Selection
for flowers
and stems
Selection
for stems
Selection
for leaves
Kale
Wild mustard
Kohlrabi
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Charles Lyell, Geologist*
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Thomas Malthus, studied populations
 Concerned about overpopulation of humans
 Competition may occur as a result
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Jean Lamarck, French Evolutionist*
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Alfred Wallace, scientist with similar ideas*
Charles Lyell
“Principles of Geology”
Earth was much older than previously thought.
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Malthus publishes
“Essay on the Principle of Population.”
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Concerned about overpopulation of humans
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Competition may occur as a result not only
for humans but other species
Jean
Lamarck
Frenchman,
Ideas of how
Organisms form
structures
“Use or
Disuse”
Hypothesis
Giraffes have long
necks because they
use & stretch them
during their lifetime.
Alfred
Wallace
Developed
similar ideas
at same time
Scientist who
Helped encourage
Darwin to
Publish his works.
Survival of the
Fittest
1.
2.
3.
4.
5.
Population has variations
Some variations are favorable.
More offspring are produced than
survive.
Those that survive have favorable
traits.
A population will change over time.
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Read carefully your assigned numbered
scenario (s) [1,2,3,or 4]
Identify Darwin’s 5 points for scenario(s)
Pair share your results with your partner
Be prepared to present your findings using
white board
Everyone reads and answers #5
DUE Today!!!
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Lab Format
 Title:
 Purpose:
 Hypothesis: (need leave space - do tomorrow)
 Materials: “as on sheet”
 Procedure: (write out a few notes as to what you
will be doing tomorrow with fabric & beads; number
of times, etc.)
 Data: (tape the data table into notebook)
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Which was the “fittest” in your habitat?
Using “Darwin’s Natural Selection WS” can
you fill in the 5 points in for your lab
simulation example?
 Population has variations.
 Some variations are favorable.
 More offspring are produced than survive.
 Those that survive have favorable traits.
 A population will change over time.
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Is your worksheet complete?
Let’s review any questions…
All answer #5
Worksheet is collected today!
 Gregor Mendel – was doing his
studies of genetics, but not
available for Darwin’s theory
 Darwin & Mendel knew organisms
had traits (characteristics), but did
not know about DNA and genes
that were inherited
What causes the variation of beetles?
 What remains the same:
 Organisms undergo evolutionary change
and are selected by their environments
over time.
 The accumulation of many changes in a
population (due to environmental
pressures) that results in the evolution of
one species of organisms into another
over time.
Genetic Variations exist within a
population
 Organisms reproduce like-organisms &
overproduce to increase survival rate
 Competition for Resources exists within
an environment
 Individuals with “selected variations” are
the most fit for the environment by
surviving & reproducing
(Survival of the Fittest)
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 Accumulation of small changes over
millions of years
 Cataloging and describing of
fossils --- is a constructed history
of life on Earth.
 See time table p51
 Video clip…
 Pattern of periods of almost no
change followed by a rapid burst of
evolution
Punctuated
Equilibrium
time
Gradualism
 Complete disappearance of one
type of organism
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Usually resulting from extreme
environmental pressures, human or
natural [See p52 examples]
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Organisms that have disappeared over time
were not “inferior” in any sense to those that
survived.
Organisms that survive & reproduce are lucky
to possess the selected variations or
adaptations.
Although natural selection is a potent force,
some species become extinct by chance or by
human intervention. It is not always a result
of poor adaptations.
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Overproduction:
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Variation and Adaptations: There is genetic
more offspring are produced than can
survive creating a struggle for existence.
variation among offspring & some variations increase
survivability for current environment.
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Survival of the Fittest:
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Biological Evolution by Natural Selection:
Nature ’selects’ those
organisms whose adaptations allow them to survive &
reproduce.
Over time, the organisms with the “favorable” adaptations will
make up most of the population.