Download Theory of Evolution FYI…Charles Darwin Theory of Evolution

FYI…Charles Darwin
Theory of Evolution
Mr. Saenz
Biology Dept
North Pitt High School
Charles Darwin came from a family of doctors, and he
almost became one, too. Both his father and
grandfather were doctors, and they urged him to
follow in their footsteps. Charles started out in
medical school but soon found that he did not like it.
He then went to theological school to study to become
a minister. Darwin had always been interested in
nature, so he also took courses in biology and
geology. These courses were the extent of his formal
training as a naturalist when he accepted a job on the
HMS Beagle. Darwin was not the most qualified
applicant, but he was hired anyway because the
captain, Robert Fitz Roy, thought Darwin would make
a good companion for the five-year voyage.
Theory of Evolution
Theory of Evolution
• Before Darwin came up with his theory he
had some ideas from earlier scientists.
Theory of Evolution
James Hutton and Charles Lyell:
• They proposed that the Earth has changed
gradually over time.
Darwin took this idea and expanded on it…
“Life has changed gradually over time”!!!
Lamarck’s Theory
Jean-Baptiste Lamarck (1809):
• French naturalist, who first recognized that living
things have changed over time and that all species
were descended from other species.
• He proposed that by selective use or disuse of
organs, organisms acquired or lost certain traits
during their lifetime. These traits could then be
passed on to their offspring. Over time, this
process led to change in a species
• Theory Status: Disproven
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Theory of Evolution
Thomas Malthus (1798):
• He reasoned that if the human population
continued to grow unchecked, sooner or
later there would be insufficient basic needs
for everyone.
• Main reason why populations cannot grow
exponentially forever (J-curve)
Theory of Evolution
What happened during his travels?
• He saw lots of biological diversity
• Ex. In a forest in Brazil he collected 68 different species
of beetles-despite the fact he was not even looking for
them.
• He noticed that even though Argentina and Australia
have similar grassland ecosystems, the animals
inhabiting those lands were different from each other.
• He collected fossil remains of ancient organisms which
resembled organisms of today.
• Found several brown birds w/ different shaped beaks
• Found some mockingbirds which were different from
each other
Back in those days…
• People believed that the Earth and all its
forms of life had been created only a few
thousand years ago. Since that original
creation, they concluded, neither the planet
nor its living species had changed.
• Many religions still do this day.
Theory of Evolution
What scientific explanation can account for the
diversity of life?
Evolution
Who was Charles Darwin?
The founder of the modern theory of evolution was
born on February 12, 1809
What was his job?
Naturalist (collect, study and label specimens)
Where did he do a lot of his onsite research?
Galapagos Island (South America)
What was the name of the boat?
HMS Beagle
Theory of Evolution
What did he later learn from his travels?
• The brown birds w/ different shaped beaks were
actually the same species
• The mockingbirds were actually different species
What did he envision?
• a theory about the origin of adaptation,
complexity, and diversity among Earth’s living
creatures
• Many found his idea brilliant, while others
strongly opposed it…WHY?
Theory of Evolution
Who was this theory?
The theory of evolution by natural selection
What is natural selection?
• Remember, since growth does not occur exponentially
forever species will struggle to exist!
• small, random, heritable differences among individuals
result in different chances of survival and reproduction
– This is called fitness
• success for some, death without offspring for others
• this leads to changes in shape, size, strength, color,
biochemistry and behavior among the descendants
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Theory of Evolution
How does it work?
• since less successful competitors produce fewer
offspring, those weaker traits disappear
• the stronger/better traits tend to increase gradually
throughout the population
What is another phrase for this?
“Survival of the Fittest”
What is artificial selection then?
• Same as natural selection, just instead of nature picking
the strong traits, man does
Biogeography
The study of the geographical distribution of living
creatures
• Species now living on different continents had
each descended from different ancestors.
• Since some animals on each continent were
living under similar conditions, they were
exposed to similar pressures of natural selection.
• Because of these similar selection pressures,
different animals ended up evolving certain
striking features
Paleontology
• Hundreds of transitional fossils that document
various intermediate stages in the evolution of
modern species from organisms that are now
extinct.
• Fossils sometimes can tell what was alive at one
time and how long ago it was
• Gaps remain
• a.k.a. “The Fossil Record”
Theory of Evolution
What is the name of the book he wrote?
The Origin of the Species by Natural Selection
What evidence does he have for this?
1- Biogeography
2- Paleontology
3- Embryology
4- Morphology
Biogeography
• If you put two different
animals in similar
environments, then the
strong traits in one area for
an animal will be the same
strong traits for the other
area for the other animal.
• This can lead to two
different looking animals
evolving to look the
same…but they are still
different species.
Beaver
Beaver
NORTH
AMERICA
Muskrat
Muskrat
Beaver and
Muskrat
Coypu
Capybara
Capybara
SOUTH
AMERICA
Coypu and
Capybara
Coypu
Embryology
• That many different organisms have many
similarities when comparing their early stages of
life.
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Morphology
Morphology
• The number of shared characteristics between
any one species and another indicates how
recently those two species have diverged from a
shared lineage
• In other words…
• The more different species look alike (or have in
common) indicates how closely related they are.
Homologous Structures
• Structures in different species which
superficially look different but are quite similar
in their foundation.
Turtle
Alligator
Bird
Mammal
Ancient lobe-finned fish
Morphology
Variations in Natural Selection
Analogous Structures
• no similarity in structure, but similarity in fxn
Vestigial Structures
• structures which now have no fxn, but once did
• vestigial structures stand as left behind evidence
of the evolutionary history of a lineage
Variation in Traits
These butterfly live
in different areas of
North America
• Traits have variation.
• Some variations of a trait increase or decrease an
organism’s chance of survival in an area.
• Variations of a trait are controlled by alleles
(genes) and can be inherited.
• Therefore, the frequency of an allele (gene) for a
trait in a populations gene pool can change due
to natural selection.
• Significant changes in the gene pool can lead to
the evolution of a new species over time.
Variations in Natural Selection
Stabilizing Selection
• average organisms have the survival advantage
in an environment
Despite their slight
variations, they can
interbreed to produce
fertile offspring
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Variations in Natural Selection
Directional Selection
• one extreme trait for a species has the advantage
for survival but another extreme does not
Variations in Natural Selection
Disruptive Selection
• either extreme trait for a species has the
advantage for survival
Patterns of Evolution
Types:
1. Macroevolution
a.
b.
c.
d.
e.
f.
Extinction
Divergent Evolution
Convergent Evolution
Coevolution
Punctuated Equilibrium
Changes in Developmental Genes
Macroevolution
• Large scale evolutionary patterns that occur
over a long period of time.
2. Microevolution
Extinction
Divergent Evolution
• Usually, it occurs due to reasons of natural
selection (Darwin).
• Sometimes events cause wipe outs of entire
ecosystems leading to mass extinctions.
• When an ancestral species evolves into an array of
species to fit a variety of habits.
• If you place 2 similar looking species in different
environments over time they will become more
different in their appearance due to the differences
in the traits needed to survive.
• This is how one species can evolve into many
different species.
• Another name for this is ADAPTIVE RADIATION
– Ex. dinosaurs
• Mass extinctions can result in a burst of
evolution that produces many new species.
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Divergent Evolution
Convergent Evolution
• When different looking species evolve similar
traits due to living in similar environments.
• If you place 2 different looking species in similar
environments over time they will become more
similar in their appearance due to the similarity in
the traits needed to survive.
• Ex. Beaver, Muskrat, Cupybara
• Ex. Shark, penguin, dolphin
Coevolution
• How two species evolve
to each others needs
over time
• Ex. The moth with the
long tongue due to the
flowers petals
Changes in Developmental Genes
• Changes in the activation of
certain genes can lead to major
evolutionary transformations.
• Ex. Ancient insect wings
compared to modern insect
wings. Due to “wingless” gene
being turned on at an insects
body segment.
• Ex. Long legs/short legs; same
for fingers
Punctuated Equilibrium
• Rapid evolution in a species
after long periods of no
change (equilibrium)
• Could indicate that evolution
is not always slow and
steady like Darwin said
• Gradualism – evolution at a
slow and steady rate.
Microevolution
• Evolution within a single population or
species.
• Tends to happen quicker
• Ex. Bacteria becoming resistant to
antibiotics.
• Ex. Insects and weeds becoming
resistant to insecticides and herbicides.
• Ex. HIV becomes resistant to AZT
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