The Evolution of an IDEA!!! Objectives: Describe the contributions of early scientists to modern theories of evolution Explain the fundamental theory of evolution Discuss some questions and ideas that shaped Darwin’s thinking

In your own words, describe what YOU think the theory of evolution means…

Charles Darwin

Darwin’s Theory of Evolution Evolution, or change over time, is the process by which modern organisms have descended from ancient organisms. A scientific theory is a well-supported testable explanation of phenomena that have occurred in the natural world.

How did Darwin came up with his theory? …well first we have to have a look at those who came before Darwin. These people changed the way we look at the world around us. Darwin’s theory was greatly influenced by the following people.

Ideas that shaped Darwin’s Thinking James Hutton: 1795 - Theory of Geological change Forces are changing the shape of the Earth’s surface These changes are very slow The Earth is much older than the thousands of years we once thought!

George Cuvier: Fossil Studies (1769 – 1832) He noted that fossils can be simple or complex Fossils of simpler organisms seem to be found in deeper layers of rock and soil Fossils of more complex organisms seemed to be found at relatively shallower depths The shallower the depth a fossil is found in, the more closely it is likely to resemble a living species He also noted that some rock layers contained fossils of organisms that didn’t occur in any other layer Theory of Catastrophism: Catastrophes like floods caused extinctions of species (which could be found in the fossil layers) and these species were replaced by new species.

Charles Lyell: Theory of Uniformitarianism 1797-1875 Published ‘Principles of Geology’ Earth has been changed in the past and is still changing now Geological change is very slow Hypothesized that mountains were and are still being formed by gradual processes and areas of land are being slowly worn/eroded away Darwin thought if the Earth changed over time, what about life on the Earth?

Lamarck

Lamarck's Principles Use and Disuse: Structures an animal used became bigger and stronger, while structures that were not used became smaller and weaker. Inheritance of Acquired Characteristics: An animal could pass on the traits it had acquired throughout its life to its offspring

What did we get from Lamarck?? Lamarck hypothesized that… All species evolve over time. A species evolves in response to its environment so that it is better able to survive (adaptation) Changes get passed on from generation to generation Lamarck’s theory, while flawed got the ball rolling for modern day thinking about how and why species change.

Population Growth – Why do species need to change??? Thomas Malthus-19th century English economist If populations grew indefinitely(more Babies born than die) Insufficient living space Food runs out Darwin applied this theory to animals

On to Darwin…The Voyage of the Beagle

Voyage of Beagle Dates: February 12th, 1831 Captain: Charles Darwin Ship: H.M.S. Beagle Destination: Voyage around the world. Findings: Evidence to propose a revolutionary hypothesis/theory about how life changes over time

Patterns of Diversity (Questions) Darwin visited Argentina and Australia which had similar grassland ecosystems. Those grasslands were inhabited by very different animals. Neither Argentina nor Australia was home to the sorts of animals that lived in European grasslands. Why??? Wouldn’t similar environments be home to similar species??

Patterns of Diversity Darwin posed challenging questions. Why were there no rabbits in Australia, despite the presence of habitats that seemed perfect for them? Why were there no kangaroos in England?

Living Organisms and Fossils Darwin collected the preserved remains of ancient organisms, called fossils. Some of those fossils resembled organisms that were still alive today.

Living Organisms and Fossils   Others looked completely unlike any creature he had ever seen. As Darwin studied fossils, new questions arose. Why had so many of these species disappeared? How were they related to living species?

Publication of Origin of Species Russel Wallace wrote an essay summarizing evolutionary change from his field work in Malaysia Gave Darwin the drive to publish his findings

Read through your hand out and answer questions 1-3. Your Task Read through your hand out and answer questions 1-3. For HOMEWORK tonight!! Read Adaptive Radiation: Darwin’s Finches to learn more about what Darwin discovered on his voyage. Answer the questions I am away tomorrow. There will be a QUIZ on Thursday based today’s lesson and your work tomorrow!

Mechanisms for Evolution Natural variation--differences among individuals of a species Artificial selection- nature provides the variation among different organisms, and humans select those variations they find useful.

Artificial Selection

Other Mechanisms that Drive Evolution Sexual Selection: the process by which a trait that enables an organism to acquire more mates becomes more common. Males compete for females (combat) Females chose males (desirable traits)

Genetic Variation Evolution requires genetic variation. New genes being introduced results in diversity of offspring. Mutations: Source of genetic variation Light and Dark Moths Dark Moths increased in frequency during industrial revolution because of dark soot in air Dark Moths could hide from birds

Descent Descent with Modification-Each living organism has descended, with changes from other species over time Common Descent- were derived from common ancestors

Evidence of Evolution The Fossil Record Comparative anatomy/Homologous Body Structures

Similarities in Early Development Biochemistry and DNA Vestigial organs Observation of Direct Species Change

Evidence for Evolution The Fossil Record-Layer show change Shows numbers extinct animals Shows similarities between extinct animals and animals that are alive today The earth’s layers show a time scale of species and when they appeared on earth (and when they died out)

Transitional fossils are fossils that show intermediary links between groups of organisms They can provide a link between the past and present

Biochemistry and DNA When comparing the DNA of one species to another, more similarities are found in species that are more closely related.

Direct observation of species change Bacteria become resistant to antibiotics Wolves were bred over many generations to become dogs (artificial selection) • and then bred further to create a variety of breeds

Your Task With your partner, review the 4 mechanisms for evolution that you learned about today. Explain each mechanism for evolution in your own words. How do you think each of these mechanisms drove evolution?