Download Charles Darwin and Evolution “from so simple a beginning, endless

Charles Darwin and Evolution
“from so simple a beginning, endless
forms most beautiful and most
wonderful have been, and are being,
evolved.” – On the Origin of Species
I. Darwin’s Travels
1. In 1831, Charles Darwin traveled on
the HMS Beagle (a ship) around the
world from England. He went to the
Galapagos Islands off of Ecuador.
2. He made observations of plants and
animals and collected specimens. This
led him to propose a revolutionary
hypothesis on evolution.
Evolution is change over time. It is the
process by which modern organisms
descended from ancient ones.
II. Darwin’s Observations
He asked questions!
- Why aren’t there any rabbits in Australia
even though climate is right?
- Why are there no kangaroos in England?
- Why is there such variety in living things,
i.e. biological diversity.
- How are species so well suited to their
habitats?
- Why had so many species disappeared?
- How are they related to living ones?
• Fossils would be the answer to many of his
questions. Fossils are the remains of ancient
organisms.
 Some ancient fossils resemble modern living
organisms.
 Some fossils didn’t look like ANYTHING
he’d seen before. WHAT HAPPENED?
 Why were there so many different types of
tortoises, finches etc. Why not just one type
since they all lived on the Galapagos Islands?
• –Islands are far apart w/ different climates,
different species.
The tortoises varied in predictable
ways from one island to another.
Shell shape and neck length could
identify the island the tortoise came
from.
• The finches on the different island had
different beaks for different foods.
• The changes in beak shape were driven by
competition for food.
•Common ancestor???
III. Darwin’s
Conclusions/Hypothesis
•These separate species of animals must have
come from one common ancestor!
IV. Ideas that Shaped Darwin’s
Thinking
• A. At this time people thought:
1. World and life were created 1000 years
ago!
2. Nothing had changed since then!
V. New Ideas
A. Hutton and Lyell: Geologists
1. Through fossils and geologic
formations showed Earth was millions of
years old and that it was constantly changing
over time.
This all influenced Darwin…
• a. If Earth could change
over time, couldn’t living
things?????
• b. IF Earth were old (like
they are saying) it would
give time for organisms to
change!!
VI. Lamarck
A. His Ideas:
• Jean-Baptiste Lamarck said (before Darwin)
that by using something a lot or not using
something, an organism acquired or lost traits
during their life. These traits could be passed
on to the babies. “Use it or lose it” theory.
• Ex. Lamarck thought that if a giraffe stretched
its neck, it could pass this longer neck onto its
baby. (Acquired = gained)
• Ex. Or, say a swimmer builds up large strong
shoulders, he/she would pass large shoulders on
to their child.
• B. Lamarck didn’t quite get it right. He didn’t
know that an organism’s behavior doesn’t
influence what traits are passed on to offspring.
He did not know about genes.
• Still, he was one of the first to develop a
theory of evolution and recognize that organisms
are adapted to their environments. He paved the
way for Darwin!
VII. Darwin Speaks Out
A. On the Origin of Species
• He didn’t publish the book for 25 years! (A
little afraid of what would happen!) ….i.e.
“dangerous” idea.
• His theory was Natural Selection AKA “Survival
of the Fittest”
• In sum: the organisms best suited to their
environment will survive.
1.Artificial Selection:
•Farmers, Breeders pick the “best” to
breed/survive!
This Chihuahua mix and Great Dane show the
wide range of dog breed sizes created using
artificial selection.
Pigs are artificially selected by man to
produce the largest amount of meat.
Evolution by Natural Selection
Survival of the Fittest:
• In biology, an adaptation is ANY
inherited characteristic that increases an
organism’s chance for survival. The
possibilities are limitless! Just look at an
organism and see how it works well in its
habitat.
 Ex of adaptations: camouflage, mimicry,
behavioral adaptations
Camouflage
- blending in with one’s
surroundings to increase
chances of survival
http://www.youtube.com/watch?v=7ch1277quZo
Mimicry- looking like another organism
to increase chances of survival
• Paper wasp
• Day flying
moth
Mimicry
»Red on yellow - kills
a fellow« or »Red
touching black - is a
friend of Jack«
Mimicry
• Monarch
poisonous
Viceroy: harmless!
Hunting in a Pack!
• Wolf Park in Battleground, IN
• In biology, fitness is the ability of an
organism to survive and reproduce.
• Organisms within a species are in a
struggle for existence, a competition
for resources like food, space, mates.
Individuals with adaptations that make them wellsuited to their environment have increased
fitness.
• They are “…harder, better, faster, stronger” –
according to Kanye.
• They could also be good at hiding
like your peppered moths! 
• Darwin called this process survival of
the fittest or natural selection.
• Natural selection is Darwin’s theory
about the mechanism for evolution, his
explanation of how it occurred. (Lamarck’s
mechanism was inheritance of acquired
traits).
Darwin called his theory natural
selection to distinguish it from
artificial selection.
 In artificial selection, humans “select” or
choose the variations that will survive and
reproduce. Ex. crops, livestock
 Darwin concluded that something like this
worked in nature.
• In natural selection, the environment
“selects” the organisms that will survive
and reproduce. These are the organisms
with the adaptations that give them an
advantage in fitness.
B. Summary of Darwin’s Theory of
Natural Selection
• 3 Ingredients: VARIATION, SELECTION, TIME!
• http://learn.genetics.utah.edu/content/selecti
on/recipe/
1) VARIATION: There is variation within a
population. (variation = some individual differences)
 Some variations are better than others (they are
adaptations that increase fitness).
2) SELECTION: The most “fit” organisms survive and
reproduce. They are “selected” by how well adapted
they are to their environment.
3) TIME: The future generations inherit the
favorable variations. Over time, the inherited
characteristics of a population change. = evolution!!!
(descent with modification)
NOTE: The variations are caused by
MUTATIONS!