EVOLUTION Review Scientists who contributed to the theory of evolution Mechanisms for evolution

Charles Darwin

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

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

How did Darwin came up with his theory?

Voyage of the Beagle

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

Patterns of Diversity (Questions) Darwin visited Argentina and Australia which had similar grassland ecosystems. 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.

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. Darwin collected the preserved remains of ancient organisms, called fossils.fossils Some of those fossils resembled organisms that were still alive today. 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. Others looked completely unlike any creature he had ever seen. As Darwin studied fossils, new questions arose. As Darwin studied fossils, new questions arose.  Why had so many of these species disappeared?  How were they related to living species?

Ideas that shaped Darwin’s Thinking James Hutton: James Hutton: 1795 Theory of Geological change 1795 Theory of Geological change  Forces change earth’s surface shape  Changes are slow  Earth much older than thousands of years

Ideas that Shaped Darwin’s Thinking Charles Lyell Charles Lyell Book: Principles of Geography Book: Principles of Geography Geographical features can be built up or torn down Geographical features can be built up or torn down Darwin thought if earth changed over time, what about life? Darwin thought if earth changed over time, what about life?

Lamarck

Lamarck’s Theory of Evolution Tendency toward Perfection (Giraffe necks) Tendency toward Perfection (Giraffe necks) Use and Disuse (bird’s using forearms) Use and Disuse (bird’s using forearms) Inheritance of Acquired Traits Inheritance of Acquired Traits Are you still paying Attention? Are you still paying Attention?

Population Growth Thomas Malthus- 19th century English economist Thomas Malthus- 19th century English economist If population grew (more Babies born than die) If population grew (more Babies born than die)  Insufficient living space  Food runs out  Darwin applied this theory to animals

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

Mechanisms for Evolution Natural variation--differences among individuals of a species 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- 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. Sexual Selection: the process by which a trait that enables an organism to acquire more mates becomes more common. Males compete for females (combat) Males compete for females (combat) Females chose males (desirable traits) Females chose males (desirable traits)

Genetic Variation Evolution requires genetic variation. Evolution requires genetic variation. New genes being introduced results in diversity of offspring. New genes being introduced results in diversity of offspring. Mutations: Source of genetic variation Mutations: Source of genetic variation Light and Dark Moths 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 Descent with Modification-Each living organism has descended, with changes from other species over time Common Descent- were derived from common ancestors Common Descent- were derived from common ancestors

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

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

Evidence for Evolution The Fossil Record-Layer show change The Fossil Record-Layer show change Shows numbers extinct animals Shows numbers extinct animals Shows similarities between extinct animals and animals that are alive today 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) 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 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 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. 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? Explain each mechanism for evolution in your own words. How do you think each of these mechanisms drove evolution?