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Evolution
a change in the genetic makeup of a species
overtime
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History of evolutionary thought
Lamarck
Inheritance of Acquired Traits:
An organism can pass along characteristics
acquired during its lifetime to its offspring
Driven by a need giraffe would continually stretch its neck until it became a little
longer. When it reproduced offspring would be born with longer necks because
that trait had been acquired already by parent.
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Charles Darwin
1831- Beginning of a 5 year exploration around the world on the
HMS Beagle
Studied the variety of life around the world
Spent a large amount of his trip in the Galapagos Islands
Made his break through discovery through the different species
of finch he found finch he found on each island.
All descended from a common ancestor
Each species evolved to optimize its adaptations for the
different environment found on the different islands
Natural Selection-The organisms best adapted to their environment
tend to survive to transmit their genetic characteristics to
succeeding generations, which results in increasing numbers of
organisms with those traits while the genetic characteristics of less
adapted organisms tend to be eliminated over time.
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How Evolution Works
Natural Selection: 4 Mechanisms
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genetic variation
over production of offspring
struggle for survival
differential survival and reproduction rates
1.Genetic Variation
-Different genes create different phenotypes.
-Advantage: More likely to pass along genes and trait
becomes more common over time
-Disadvantage: Less likely to pass along genes and trait
diminishes over time
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2. Overproduction of offspring :
Most organisms produce many more offspring than can be
supported by the environment
3. Struggle for survival:
-Predator/Prey Relationships
-Limited Resources
-food, shelter, water, territory, sunlight
-Environmental Challenges
-Temperature, Disease, Pollution, etc.
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4. Differential Survival and Reproduction Rates
-Different Traits create advantages/disadvantages to an
organisms ability to survive and to reproduce
Survival Traits: Coloring, Physical Traits, Heightened Senses
http://www.youtube.com/watch?v=
9iQwKYi6ytg&feature=bf_prev&list=PLCC07E66503F99BB5&lf=results_main
Physical Traits- Stronger, Faster, Bigger/Smaller, Growth Rate
http://www.youtube.com/watch?v=FfDOMwFX5Hg&feature=results_main&playnext=1
&list=PLCC07E66503F99BB5
Heightened Senses-Better eyesight, sense of smell, hearing, etc.
Types of Coloring:
Mimicry- When an organism attempts to look like another
organism (Copycat)
Aposematic- When an organism is brightly colored or has highly
contrasting marking to warn other organisms to stay away
(WARNING!)
Cryptic- When an organism is coloring allows it to blend in with
its environment (Camouflage)
Counter Shading- When an organism is colored darker on its
back
and lighter on its front to limit it being seen from
above and below (darker back lighter stomach)
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Mimicry
Elephant Hawk Moth
caterpillar
Dead Leaf
Butterfly
Owl Butterflies
Red Milk Snake (non-venomous)
King Snake (venomous)
Hawk Moth
Alligator Snapping Turtle
Death Adder
Leafy Sea Dragon
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Aposematic
Poison Dart Frogs
Saddleback Caterpillar
Monarch Butterfly Caterpillar
Stinging Rose Caterpillar
Spiny Oak Slug Caterpillar
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Cryptic Screech Owl
Flounder
Arctic Fox
Leopard
Spotted Eel
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Counter­shading
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Differential Survival & Reproduction Rates Cont'd.
Sexual Selection: Ability to attract/get a mate
-2 types
-Between Same Sex (Males)
-Attracting Opposite Sex (attracting female)
http://app.discoveryeducation.com/player/view/assetGuid/841DDC20­C7AE­467F­A1A5­
E731E264B1E5
http://dsc.discovery.com/videos/planet­earth­jungles­birds­of­paradise.html
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Natural Selection: "Survival of the fittest."
-What does fittest mean?
Bigger, Stronger, etc.?
Best at hiding from
predators?
Ability to attract mate?
Fittest: The organism that is best adapted to its conditions to survive
to pass its genes to the most offspring compared to other organisms
of the same species.
Who is the most fit?
Lived 20 years
Offspring: Simba
Lived 30 years
Offspring: None
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How do we know evolution exists?
Evidence for Evolution
-Fossil Record
-Biogeography
-Chemical & Anatomical Similarities
-Documented changes in living species
Examing the Fossil Record:
Strata-the layers of soil and rock deposited over time
Creating a continuum of life through strata
The deeper the strata the older it is--fossils found in
deeper layer are from older species
Radioactive Dating
-Using naturally occurring radioactive isotopes (in rocks, fossils,
organic matter, etc.) to find the age of the item the isotopes are
contained in
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Radioactive Dating
Isotopes- Different versions of the same element that have the same
atomic number but different atomic masses
Ex. Carbon 12, 13, 14 (atomic mass)
Carbon has six protons (atomic number)
Carbon 12 has 6 protons 6 neutrons
Carbon 13 has 6 protons 7 neutrons
Carbon 14 has 6 protons 8 neutrons
Radioactive Isotopes-isotopes that are unstable and decay (change by
breaking down) to a stable isotope of something over time
Half-Life: The amount of time it takes for 1/2 of the radioactive
isotopes to decay.
How old is a fossil that currently has 12.5 % of its
original C14?
5, 730 years per half life x 3 half lives+ 17,190 years old
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RHEA
OSTRICH
EMU
Biogeography
Biogeography- The study of the distribution of species around the
world and through history
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Chemical and Anatomical Similarities Between Species
Chemical Similarities: The amount of DNA sequences that are
similar between different species
-The more recent the common ancestor the more
similarity between genome (total DNA)
Anatomical Similarities: members of the same class of animals tend
to have similar structures and organs, even though they may
not look the same externally.
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Observed Changes In Living Organisms
MRSA- Multidrug-Resistant Stapphylococcus Aureus
Majority Light
Industrial Revolution
Majority Dark
Majority Light
Anti-Pollution
Legislation Passed
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Role of fitness in speciation
Speciation- Evolutionary process where new species arise
Species- Organisms capable of interbreeding and producing fertile
offspring
Population Genetics:
Disruptive Selection:
Often results in 2 new species
Stabilizing Selection:
Reduces variations­ no new species
Directional Selection:
Often results in new species
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