Transcript Unit 8: Origin of Life and Evolution

Origin of Life and Evolution
What is Evolution
• Evolution is the change in the gene frequency
of a population over time
• Basically, it is the change of a population over
time.
• If we can show you populations changing over
time, then we can show you evolution.
Quiz
• 1) Define Evolution
Evidence of Evolution
• Do we have evidence of populations changing
over time?
• Yes! What are some of those pieces of
evidence?
Fossils
• Fossils are the remains or evidence of a once
living organism.
• There are many types of Fossils. Let’s go over
some of them.
Fossils, part 2
• Mold Fossil: a mold is left behind. Like
fossilized foot prints.
• Cast Fossil: something fills the mold and
eventually forms a rock.
Fossil, 3
• Permineralization: minerals fill in the pores of
a living organism. Eventually, the minerals are
left behind: petrified wood.
• Replacement fossisl: the organism is
eventually replaced by minerals. Like a
mineral photograph.
Fossil, 4
• Preservation: parts of the organism is left
behind and preserved: insects in amber,
animals in glaciers, organisms in tar pits…
Quiz
• 2)Define fossils:
• 3) What are 3 of the 5 types of fossils?
Comparative Anatomy:
Homologous
• Compare body parts of different organisms.
• If the organisms shared a common ancestor,
but they lived in different environments, they
would be HOMOLOGOUS.
• Homologous structures have a similar set up,
but look bit different.
Comparative Anatomy: Analogous
• Analogous structures are found in organisms
that don’t have a common ancestor, but live in
a similar environment. These organisms had a
similar solution to the same problem.
Comparative Anatomy: Vestigial
• Vestigial Structures are structures that have
no function. You might assign a function, but
the only thing that these structures do is not
kill the host.
Comparative Biochemistry
• Compare the DNA/proteins of an organism. If
the DNA/proteins are similar, then they shared
a common ancestor.
Quiz
• 4) What can you say about the structures of
Homologous structures?
• 5) What can you say about the structures of
Analagous structures?
Now what
• We have the evidence that populations have
changed over time, but HOW DID THE
POPULATIONS CHANGE?
• There are two main theories, that were
proposed by two different individuals.
History of Evolution
• 1809 – Jean Baptiste Lamarck
• He had two theories:
– Law of Acquired Characterisitics
– Use it or Lose it.
Law of Acquired Characteristics
• Organisms can change their traits during their
lifetime and pass on these traits to their
offspring.
• Examples:
Law of Use and Disuse
• If you don’t use it, you will lose it.
• Ex: by trying to use their front limbs to fly,
birds could transform those limbs into wings;
birds that don’t use their wings would
eventually lose them
Was Lamarck right or wrong?
• Lamarck’s ideas were wrong, but he was one
of the first to propose an evolutionary theory
Quiz
• 6) What were Lamarck’s two laws?
Charles Darwin
• Originally in Medical School: Didn’t like the
sight of blood.
• Was thinking about becoming a pastor, so he
could study science.
• Needed a direction in life.
A party that changed everything
• Darwin went to a party.
• Met Captain FitzRoy. He was the captain of the
HMS Beagle and needed a Gentleman
Companion. He could talk to anyone on the
ship. FitzRoy was worried about going
crazy…his uncle killed himself (slit his own
throat)
• Darwin was the right social class.
Darwin agrees to go on the voyage
• In 1831, Darwin agrees to go on the 5 year
voyage on the Beagle.
• Found out that he hated FitzRoy.
• Was the Unofficial Naturalist. Official
Naturalist: the ship’s doctor: McKormick.
• McKormick was jealous of Darwin and quit in
the middle of the voyage.
Charles Darwin visits the
Galapagos
• Archipelago off the coast of Ecuador.
• Noticed that the characteristics of animals
(finches) varied among the Galapagos Islands
Finches
• Noticed that the beaks of the finches varied
on the different islands due to the different
foods that they ate.
Thinking about Natural Selection
• Darwin got back in 1836 and wrote about his
new theories. It took him 23 years to write
The Origin of Species by Means of Natural
Selection.
Alfred Wallace
• Alfred Wallace also came up with the theory
of Natural Selection. Darwin and Wallace
published at the same time, but Darwin wrote
a book. Darwin got famous!
Quiz
• 7) What was the name of the ship that Darwin
sailed on?
• 8) What was the name of the book that
Darwin wrote?
Natural Selection
• Explains how GROUPS/populations of
organisms change over time
• Individuals do NOT evolve (Ex. you cannot
“evolve” yourself to become 5 feet taller by
next week)
• Individuals have 3 choices: Adapt, Migrate or
Die.
Darwin’s 5 Principles of Natural
Selection
1) Individuals of a Population Vary.
This is the most important aspect of Darwin’s
principles. Variation in the population drives
evolution.
2) These variations are inheritable. You can pass
these differences to your kids.
Principle’s continues
3) There are more individuals produced that the
environment can support.
4) There is competition for the resources: There
is a struggle to survive.
Last Principle
5) The organism with the favorable traits will
survive and pass on the traits to their
offspring.
Source of Variation
Variations arise from:
– Mutations
– Sex: Gene shuffling (crossing over), the shuffling of
chromosomes, and the joining of two unique
gametes will produce a unique individual.
Quiz
• 9) What three choices do individuals have?
• 10) What are Darwin’s 5 principles of Natural
Selection?
Fitness
How successful an organism is in reproducing. The
more fit you are, the more kids you have.
Over time
• Natural selection results in changes in the
inherited characteristics of a population.
• These changes increase a species’ fitness in its
environment. (can have more kids)
Why is it called Natural selection?
• Darwin saw how similar it was to artificial
selection
• Artificial Selection – humans “select” which
individuals to reproduce (selective breeding)
ex: different breeds of dogs
Natural Selection…..
Original Population (bugs)
Predator
Those that survived reproduced, making them more fit
There is a change in allele frequency over time
= evolution
Over time, what do you think might happen?
Quiz
• 11) Define Fitness:
• 12) What is Artificial selection?
Patterns of Evoltuion: Divergent
Evolution
• When two or more related species become
more and more different from each other.
• EX: peppered moths of England (dark moths
prevalent in sooty cities, light moths common
in unpolluted rural areas)
Darwin’s Finches
Warbler finch
Cactus finch
Woodpecker finch
Sharp-beaked finch
Small
insectivorous
tree finch
Large
insectivorous
tree finch
Small
ground
finch
Cactus
eater
Insect eaters
Medium
ground
finch
Seed eaters
Vegetarian
tree finch
variation
Bud eater
natural selection for best
survival & reproduction
Large
ground
finch
Patterns of Evolution: Convergent
Evolution
• When two unrelated species come to have
similar traits because they have the same
environment (selective pressures).
• EX: aardvarks, anteaters, and pangolins all
have sharp claws, long snouts, and sticky
tongues to catch insects, but they evolved
from three completely different mammals.
Patterns of Evolution: Co-Evolution
• Shows how two separate species that interact,
over time, evolved to be interdependent on
each other
• Ex: Flowers that have coevolved with bats are
light in color. Therefore, bats, which are active
at night, can easily locate them.
• The flowers also have a fruity odor attractive
to bats.
Quiz
• 13) What is Divergent Evolution?
• 14) What is Convergent Evolution?
Speciation
• Speciation - when one species evolves into
two separate species that cannot reproduce
with each other.
• Species: When two species cannot have
FERTILE offspring.
Speciation
• Allopatric Speciation:
– A population is separated by a geographical
barrier: canyon, river, forest, glacier, ocean…
– Each population is exposed to a different
environment.
– Each population will undergo natural selection.
Speciation, part 2
• The populations will diverge and the
organisms will have homologous structures.
• If the populations could get back together,
they couldn’t produce fertile offspring.
Why?
• Prevent the formation of a fertilized egg:
– Differences in geographic location, breeding
times, breeding behaviors, mechanical
differences, and differences in gametes.
What if the egg is fertilized
• The embryo might not develop….wrong
proteins.
• The embryo might develop, but will be sterile,
the chromosomes can form homologous
chromosomes in meiosis.