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What is EVOLUTION?. What do you already know?. K-W-L Chart. What questions do you have about evolution?. Evolution is the UNIFYING THEORY OF BIOLOGY because it helps us explain and understand the DIVERSITY of life on the planet. In your own words: define diversity :. Here is a clue!.
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What is EVOLUTION? What do you already know? K-W-L Chart
Evolution is the UNIFYING THEORY OF BIOLOGY because it helps us explain and understand the DIVERSITY of life on the planet. In your own words: define diversity: Here is a clue!
Consider the following observations: Lions live in Africa Tigers live in India. How are they similar? How are they different?
If you put a lion and a tiger together in a zoo, they can have babies. We call them ligers. How does evolution explain this?
"nothing in biology makes sense except in the light of evolution” ~Theodosius Dobzhansky (1900-1975) Photo by “davemee” flickr creative commons
In science, theories are statements or models that have been tested and confirmed Theories…. • Explain data and observations • Can be used to make predictions • Are not absolute, and can be changed
How does the theory of evolution help us answer these questions? • Why do so many different animals have the same structures, the arm bones in a human are the same bones as a flipper in a whale? • Why is the sequence of DNA very similar in some groups of organisms but not in others?
The Theory of Evolution can also make a prediction. Do these animals lay eggs? Photo courtesy of Swamibu, Flickr Creative Commons
The definition of evolution… Evolution - change over time • organisms came from preexisting organisms
Time to take notes! Words you should know: Diversity Unifying Theory Evolution
Charles Darwin developed the Theory of Evolution byNATURAL SELECTION (sometimes called “survival of the fittest”)
Earlier Theory …. Lamarke's Theory of Acquired Characteristics Some thought that you would gain or lose features if you overused or didn't use them !! INCORRECT !! Photo courtesy of ucumari, creative commons, flickr
Darwin History • H.M.S. Beagle • traveled to the Galapagos Islands • Studies flora and fauna
Marine Iguana, photo courtesy of mtchm, flickr creative commons Blue-footed booby, photo courtesy of stirwise, flickr creative commons
Finch, photo courtesy of stirwise, flickr, creative commons Giant tortoise, photo courtesy of Planetgordon, flickr creative commons
Checkpoint 1. Darwin traveling to which islands? 2. What was the name of his ship? 3. Name 4 species he observed on the islands. 4. He developed what theory? 5. This theory explained how organisms _______________ over _________
Each was adapted to eating a particular type of island food He concluded that all came from one ancestral species Video on Galapagos Finch Evolution by HHMI Cactus finch, photo courtesy of zrim, flickr creative commons
1859, Darwin publishes a book called: “The Origin of Species”
Key Points to the Theory of Evolution by Natural Selection 1. Variation among individuals.2. Competition for resources 3. Competition leads to death or survival4. Those with advantageous variations are more likely to survive and reproduce.
This process came to be known as Natural SelectionThe favorable variations are called Adaptations What adaptations do tigers have? Humans? Snakes?
So how does natural selection work? Say in a species of blob….there exists blobs of all shapes and sizes (variation) Blobs eat the little purple organisms that live underground and on the surface.
During a particularly hot year, food became less abundant (competition), blobs that had the ability to dig into the soil to get food had a better chance of survival. Many blobs died that year…….
The ones that survived mated and passed their genes to the next generation. (reproduction)
The next generation had move blobs with the pointed noses. That is NATURAL SELECTION. • Variation • Competition • Survival • Reproduction
Darwin proposed that each living species was descended with changes from other species This idea is known as DESCENT WITH MODIFICATION or COMMON DESCENT
Artificial Selection - humans selected variations they found useful and bred animals and plants for those traits.
Much of our agriculture (food, animals, clothing) is a result of artificial selection that has occurred over many generations. We can influence the EVOLUTION of a species
Checkpoint 1. What was the name of Darwin’s book? 2. The theory states that a) individuals of a species have differences, called_________ b) these individuals ________________ for resources c) some will die, others will ____________________ d) survivors will _________________________ and pass traits to offspring 3. Any trait that helps an organism survive is called an _______________________________ 4. When humans influence evolution by breeding for desired traits, it is called _______________________________
Theory of Evolution -- evidence 1. Fossils 2. Homologous structures 3. Vestigial organs 4. DNA 5. Embryos 6. Direct Observation
1. Fossil Evidence shows….. -similarities between extinct animals and living animals -earth’s layers, and species that lived at each time
Dinosaurs have always fascinated us, movies such as Jurassic Park capitalize on that fascination. How do we know what dinosaurs looked like? We create a picture based on the bones we find (fossils) and use modern reptiles to guess at their texture and skin color.
2. Homologous structures – parts of the body that are similar, but have different functions All forelimbs of vertebrates have the same pattern of bones
Vestigial Structures – these are organs or parts that seem to have no function Whales have pelvic bones that do not attach to legs Watch a short video clip on whale evolution at PBS
Biochemistry and DNAWhen comparing the DNA of one species to another, more similarities are found in species that are more closely related. Lion photo credit: ucumari Tiger photo credit: digitalART2
Embryological Development Embryos of different species develop in almost identical ways. Human fetus at 8 weeks
Direct observation of species change • Bacteria become resistant to antibiotics • Wolves were bred over many generations to become dogs (artificial selection)
Checkpoint: 1. ____________ evidence shows when organisms lived on the earth 2. Species that are closely related will have similar _______ 3. A _______________ organ is one that has no function. 4. _________________ structures look the same but have different functions, like the arm of a human and the flipper of a whale. 5. ____________ of different animals develop in the same way.
How Do New Species Form? Speciation = the formation of a new species Species = group that can interbreed, produce fertile offspring.
Small changes cause a change in the appearance over time. One species splits into two species.
New species evolve as populations become ISOLATED from each other
Create your own graphic of evolution. 1. Draw 4 islands similar to the ones pictured below2. Imagine a kind of animal that would be adapted to each habitat
Adaptive Radiation - one species becomes many species - Finches in the Galapagos
