Transcript File

How have cell phones changed over time?
Evolution of the Cell Phone
Evolution of Batman
Evolution
• Change over time
The History of
Biological
Evolution
Historical Thoughts on Evolution
• Aristotle (384-322 BC): derived a concept called Scala
Naturae – “Great Chain of Being” or “The Ladder of Life”
– Hierarchical chain starting with God & progressing
downward to less complex organisms
• Literal Biblical view: the world was created in 6 days
– Earth is 6,000 years old.
– All species were created as they are today.
The Development of Modern Views on Evolution
• By the 17th century, scientists had rejected Aristotle’s theory.
• Most scientists accepted that evolution was occurring, they
just didn’t know how it was happening.
• In the 1800s, modern theories of evolution began to develop.
• The theory of evolution that we accept as true today was
influenced by many fields of study.
Influences from Geology
• Charles Lyell (1833): geological processes occurring now
are the same geological processes that shaped Earth’s
physical features over long periods of time.
– The present is the key to understanding the past.
– Influential in Darwin’s work
Influences from Economics/Sociology
• Thomas Malthus (1798): population
size linked to poverty & disease
• If the human population continued to
grow unchecked (grow exponentially),
it will be limited by space & food
supply.
Population Growth Chart
• Carrying Capacity: the maximum # of individuals in a
population that can be supported by a particular
environment
Malthus believed that as the human population neared its carrying
capacity, disease, lack of food, etc. would increase & the human
population would steady.
Sea turtles lay hundreds of eggs, but only a few
survive.
WHY?
Trees produce hundreds of seeds, how many actually
mature?
WHY?
Jean-Baptiste Lamarck (1809)
Inheritance of Acquired Traits
• One of the 1st to propose a mechanism
to explain why organisms change over
time.
• Believed that organisms would gain or
lose features if they overused or did not
use the traits
– If you don’t use it, you lose it!
– These traits could be passed on to their
offspring.
Lamarck’s Hypothesis
Organisms would gain or lose features if they overused or
did not use the traits, & they could pass these new
traits on to their offspring.
Scientists knew that snakes had probably evolved from lizards.
But how?!
Lamarck thought that there was a lizard who didn’t
use its legs, so the legs got smaller & smaller.
This lizard’s offspring would be born
without legs.
Lamarck’s Hypothesis
• Tendency Toward Perfection
– Organisms are continually changing & acquiring features
that help them live more successfully in their
environments.
• Use & Disuse
– Organisms could alter the size or shape of particular
organs by using their bodies in new ways.
• Inheritance of Acquired Traits
– Any changes could be passed down to offspring.
The evolution of Fiddler Crabs according to
Lamarck:
Do you agree with Lamarck’s hypothesis?
A. Yes - I agree!
B. No - I don’t agree!
WRONG!
Lamarck’s Hypothesis
Not supported by scientific evidence…
How did his hypothesis positively influence
evolutionary thought?
• His hypothesis on evolution was incorrect in several
ways.
• BUT he was the 1st to recognize that organisms are well
suited to their environment!
– Key concept for future work!
Charles Darwin
• In 1831, sailed on the H.M.S. Beagle around the world
– Collected plants, animals, fossils, OBSERVED
Darwin’s Observations
Species on the Galapagos Islands
were similar to the mainland, but
differ in each environment.
There are several types of finches
in the Galapagos. They’re similar
to the finches found in Ecuador,
but each is a little different.
Darwin’s Questions
About the Finches
Finches differed from island
to island. Why?
Did all these species evolve
from one species of finch?
How did the finches change
over time?
Darwin’s Observations
• Variation exists within a population
& some of that variation is
inheritable.
Some peppered moths carry the gene
for white coloration, but some carry the
gene for black coloration.
Which moths do you think will survive
to pass on their genes?
Darwin’s Observations
• Similar habitats around the world
don’t have the same animals &
plants, but the animals & plants
have similar characteristics for
that environment.
Capybara
Beavers are found in North America, while
Capybaras are found in South America.
Both species live in watery environments,
& therefore have similar characteristics
(like webbed feet).
Beaver
Darwin was influenced by Malthus’ work.
• Darwin thought that since plants & animals have more
offspring than humans, the “Struggle for Existence”
would apply more strongly to plants & animals.
If all finches ate the same
type of food, there would
be too much competition.
Darwin was also influenced by Lyell’s work.
• Darwin realized that if the Earth could change over time,
life itself might change over time in response to physical
changes of the Earth & that the changes he proposed
would require many, many years.
Darwin’s Theory of Evolution
• 1859: Charles Darwin
published On the Origin of
Species by Means of Natural
Selection
• He believed that populations
evolved by a process called
natural selection.
Evolution by Natural Selection
• Evidence for this hypothesis has
been described in many studies
& is well supported.
• Darwin’s original hypothesis is
now known as the Scientific
Theory of Biological Evolution.
Lamarck vs. Darwin
• Both Darwin’s & Lamarck’s hypotheses support
evolution, but they differ in how evolution occurs.
How is Darwin’s theory of
evolution different from
Lamarck’s hypothesis?
How did elephants get their long trunks?
Put both sets of cards in order, then try to decide whose
theory is whose.
Which one is Darwin? Which one is Lamarck?
Darwin or Lamarck?
Lamarck!
Darwin or Lamarck?
Darwin!
Studies that Support Darwin’s Theory of
Natural Selection
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Fossil Record
Population Genetics
Animal Behavior
DNA Fingerprinting
Antibiotic Resistance in
Bacteria
Before you leave…
• On a sheet of paper (share!), write your response to the
following:
Thomas Malthus believed that the human population would
naturally be kept in check by lack of food, disease, etc.
Do you believe that this is happening to the human
population today? Why or why not?