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Evolution

Explore the concepts of Lamarck's theory of evolution, Darwin's observations, natural selection, and descent with modification. Learn about the evidence of evolution and the driving force behind species adaptation. Discover how life on Earth has evolved over time.

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Evolution

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  1. Evolution Diversity of Life

  2. Lamarck’s Theory of Evolution • Use & Disuse - The Size Or Shape Of Body Organs Can Be Changed Due To Use Or Disuse • Blacksmiths & Their Sons (muscular arms) • Giraffe’s Necks Longer from stretching)

  3. Voyage of the Beagle Charles Darwin • Naturalist • 5 Year Voyage around world, HMS Beagle • Avid Collector of Flora & Fauna • Astounded By Variety of Life

  4. The Galapagos Islands • Small Group of Islands 1000 km West of South America • Very Different Climates • Animals On Islands Unique • Tortoises • Iguanas • Finches

  5. The Galapagos Islands • Finches on the islands resembled a mainland finch • Finches had different types of beaks adapted to their type of food gathering

  6. Darwin’s Observations • Patterns of Diversity were shown • Unique Adaptations in organisms • Species Not Evenly Distributed • Australia, Kangaroos, but No Rabbits • S. America, Llamas

  7. Darwin’s Observations • Both Living Organisms & Fossils collected • Fossils included: • Trilobites • Giant Ground Sloth of South America This species NO longer existed.What had happened to them?

  8. Definition • Evolution is the slow , gradual change in a population of organisms over time

  9. Darwin’s Observations • Left unchecked, the number of organisms of each species will increase exponentially, generation to generation • In nature, populations tend to remain stable in size • Environmental resources are limited

  10. Darwin’s Conclusion • Production of more individuals than can be supported by the environment leads to a struggle for existence among individuals • Only a fraction of offspring survive each generation • Survival of the Fittest

  11. Darwin’s Observations • Individuals of a population vary extensively in their characteristics with no two individuals being exactly alike. • Much of this variation between individuals is inheritable.

  12. Darwin’s Conclusion • Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals • Called Natural Selection

  13. Darwin’s Theory of Evolution • The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations (natural selection) • New species evolve

  14. Common Descent with Modification • Darwin proposed that organisms descended from common ancestors • Idea that organisms change with time, diverging from a common form • Caused evolution of new species

  15. Natural Selection • Driving force for evolution • During the struggle for resources, strongest survive & reproduce • Idea that at least some of the differences between individuals, which impact their survival and fertility, are inheritable .

  16. Evolution By Natural Selection Concepts • The Struggle for Existence (compete for food, mates, space, water, etc.) • Survival of the Fittest (strongest able to survive and reproduce) • Descent with Modification (new species arise from common ancestor replacing less fit species)

  17. Survival of the Fittest • Fitness • Ability of an Individual To Survive & Reproduce • Adaptation • Inherited Characteristic That Increases an Organisms Chance for Survival

  18. Survival of the Fittest • Adaptations Can Be: • Physical • Speed, Camouflage, Claws, Quills, etc. • Behavioral • Solitary, Herds, Packs, Activity, etc.

  19. Survival of the Fittest • Fitness Is Central To The Process Of Evolution • Individuals With Low Fitness • Die • Produce Few Offspring Survival of the Fittest AKA Natural Selection

  20. Survival of the Fittest Key Concept Over Time, Natural Selection Results In Changes In The Inherited Characteristics Of A Population. These Changes Increase A Species Fitness In Its Environment

  21. Descent With Modification • Takes Place Over Long Periodsof Time • Natural Selection Can Be Observed As Changes In • Body Structures • Ecological Niches • Habitats

  22. Descent With Modification • Species Today Look DifferentFrom Their Ancestors • Each Living Species Has • Descended • With Changes • From Other Species • Over Time

  23. Descent With Modification • Implies • All Living Organisms Are Related • Common Descent • All Species, Living & Extinct, Were Derived From Common Ancestors

  24. Evolutionary Time Scales Macroevolution:Long time scale events that create and destroy species.

  25. Evolutionary Time Scales Microevolution: Short time scale events (generation-to-generation) that change the genotypes and phenotypes of populations

  26. Evidence of Evolution Key Concept Darwin Argued That Living Things Have Been Evolving On Earth For Millions of Years. Evidence For This Process Could Be Found In: • The Fossil Record • The Geographical Distribution of Living Species • Homologous Structuresof Living Organisms • Similarities In Early Development

  27. Fossil Record • Earth is Billions of Years Old • Fossils In Different Layers of Rock (sedimentary Rock Strata) Showed Evidence Of Gradual Change Over Time

  28. Geographic Distribution of Living Species • Different Animals On Different Continents But Similar Adaptations To Shared Environments

  29. Homologous Body Structures • Structures That Have Different Mature Forms But Develop From The Same Embryonic Tissues • Strong Evidence That All Four-Limbed Animals With Backbones Descended, With Modification, From ACommon Ancestor • Help Scientist Group Animals

  30. Homologous Structures

  31. Similarities In Early Development • Embryonic Structures Of Different Species Show Significant Similarities • Embryo – early stages of vertebrate development

  32. Chicken Turtle Human Rat

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