Transcript 10 Evolutionx

Evolution
Evolution
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Change over time
Gradual
Large groups (not individuals)
Theory
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Well – supported
TESTABLE explanation
Not just an “I have a
theory”
Idea/Opinion not Theory!!!
Theories can change
Theories can be false
Charles Darwin
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Born in England
Set Sail and traveled (H.M.S.
Beagle 1831)
Recorded MANY observations
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Which became evidence
To support how life changes over
time.
WROTE everything down!
ANALYZED everything!
Charles Darwin
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He noticed how plants and animals seem to be adapted
to their environments.
AND how some environments, even though identical, had
many different plants and/or animals.
Charles Darwin
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Didn’t only look at LIVE plants and animals
Fossils
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Preserved remains of ancient animals.
Movie
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http://video.nationalgeographic.com/video/player/places/pa
rks-and-nature-places/coasts-andislands/ecuador_galapagos.html
Galapagos Islands
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Land Tortoises (GIANT)
Marine Iguanas (land too)
Birds (Darwin’s Finches)
Belief of the Time
Was believed during Darwin’s time, that the Earth had
only been formed a few thousand years before
AND
 That NOTHING had ever changed!
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James Hutton and Charles Lyell
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First to say that Earth is many millions years old.
1795 – Geological Theory (Hutton)
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Change on the Earth happens slowly
Rain, Heat, Cold bury or push up the Earth
1830 – Lyell wrote Principles of Geology
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Scientists must explain past events by processes that can be
OBSERVED.
Because what happened then, happens now.
Principals of Geology
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Darwin read this book while on the H.M.S. Beagle
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Remember: Written by Charles Lyell
He saw rocks raised from the sea floor (that had muscles
on them) that were now mountains
He concluded the same ideas (Lyell had) would
effect/change life too (not just rocks/land).
Lamarck’s Theory of Evolution
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Jean-Baptiste Lamarck – French Naturalist
1809 Published his theory (Year Darwin was born)
States:
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Organisms adapt to their environment
Use a feature – keep it
Bird Wings (Ostrich/Falcon)
Don’t use a feature – lose it.
Everything evolves towards perfection and complexity.
Inheritance
Did not know that behavior does NOT influence inherited
characteristics.
Lamarck’s Theory of Evolution
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But… Lamarck believed that everything evolved toward
perfection and that just by needing something to
survive, it would appear.
Thomas Malthus
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1798 – Theory of Population Growth
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If Human populations grow unchecked, we would run out of
room (living space) and food.
What keeps us in check?
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War (Violence), Famine (lack of food), Disease
Basically – Death!
Charles Darwin
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Realized that Malthus’ Theory of Population Growth
applies to plants and Animals even more strongly.
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Maple Trees – 1,000’s of seeds in one summer
Oysters – 1,000,000’s of eggs each year
Yet we are not over-run by oysters or maple trees
MORE die than survive.
H.M.S. Beagle
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Darwin sailed from 1831-1836
What did he return with?
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Specimens
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Plants AND Animals
Notes/Observations
Books of Data
5 Years of Data!
Darwin’s Ideas
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Were RADICAL for their time
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So radical, he was afraid of what would happen if he went
public
So he only discussed them with his friends.
His manuscripts were published AFTER he died.
AND he knew there were some things he could not
explain.
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He wrote that if the missing links weren’t found, to disregard
much of his work
Because he made some HUGE ASSUMPTIONS.
Alfred Russel Wallace
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Naturalist
Who in 1858 summed up much of Darwin’s thoughts
from the previous 25 years
They did not know each other!
What do you think that did for Darwin?
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Gave him the incentive and the initiative to publish his own
work.
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SOME of it at least.
On the Origin of Species
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Includes information on Natural Selection
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Process of evolution
Over millions of years
And continues now
Remember: Evolution is change over TIME.
Natural Variation
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Differences among species
WE are all different
Fruit, milk, production, size
All inherited!
Selective Breeding
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Farmers and breeders pick the BEST to breed for the
qualities they want.
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Produce the BEST crops, the BEST animals
This is known as Artificial Selection
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Not “natural” mating patterns – humans CHOOSE.
Natural Selection
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In Nature – the struggle to exist
Malthus’ work on population growth fits into this.
Is there enough food, space, necessities, traits
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Examples:
Speed (are you fast enough to avoid being eaten?)
Visibility (can you be seen?)
Survival of the Fittest
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Fitness
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Is the ability to live and reproduce
Need to ADAPT
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Need to change
Adaptations are evolution!!!
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Better Suited to live in their environment
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Example: Marine Iguanas
If you don’t adapt/change then you die
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You die, then you produce no offspring (or just a few before you die)
Keys to Evolution!
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Natural Selection
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Survival of the Fittest
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Generations compete to Survive and Thrive (have
offspring)
OVER TIME:
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Natural selection CHANGES organisms – they evolve –
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This is called Decent with Modification
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This
another –
IMPLIES that ALL organisms are related to one
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They have Common Descent.
Excerpt from the book (Page 382)
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“ Descent with modification also implies something else:
that all living organisms are related to one another. Look
back in time, and you will find common ancestors shared
by tigers, panthers, and cheetahs. Look farther back, and
you will find ancestors that these felines share with
horses, dogs, bats and primates. Father back still are the
common ancestors of mammals, birds, alligators, and
fishes. If we look far enough back, the logic concludes, we
could find the common ancestors of all living things. This
is the principle known as common descent. According to
this principle, all species – living and extinct – were
derived from common ancestors.”
Excerpt from the book continued (Page 382)
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“Carry the concepts of descent with modification and
common descent to their logical conclusion, and what do
they produce? A single ‘tree of life’ that links all livings
things on Earth. Darwin conceived this idea long before
he published his theory of evolution.”
THIS is the controversy!
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This is a HUGE jump – there are missing links and
assumptions that still have not been answered.
Is there evidence of evolution all around us?
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Yes!
Does that mean we came from apes?
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You decide!
What does the Fossil Record show?
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(Ancient remains that are preserved.)
Shows similarities in animals
Some look the same, some do not – but STRUCTURES
are similar
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Homologous Structures
Vestigial Organs
37 day old fetus
Humans Have Tails!
Homologous Structures
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Different mature forms, but develop from the same
embryonic tissues
Vistigial Organs
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Structures that don’t develop into mature forms
Summary of Darwin’s Theory (Page 386)