Darwin’s Theory of Evolution Chapter 15 Darwin’s Theory of Evolution

Question of the day What was the name of Darwin’s Boat? H.M.S. Beagle Where did it go? All over the world and back.

Ch. 15 Essential Questions Why did Darwin explore the world? Who shaped Darwin’s thinking? What is Artificial & Natural Selection? What is Evolution?

15-1 Evolution What is Evolution? Change over time Darwin - Modern organisms descended from ancient ones He found enough evidence to make a theory

Darwin’s Travels Originally voyage was to survey Brasil and S.A. Not intended for scientific study Darwin was along for the ride Visited places like: Galapagos Islands Falkland Islands Tahiti

Darwin’s Observations Patterns of Diversity Organisms were different between islands They were well adapted to environment Organisms & Fossils Found preserved remains that resembled modern species Specialization Organisms developed special traits or habits to survive in an area

Darwin’s Influences Hutton & Lyell Geology Evolution of Earth’s environment By natural events Time, disasters, weathering, etc.

Darwin Thanks Lamark Darwin “borrows” theories from naturalist Organisms evolve to be more complex & perfect Use or disuse of limbs, behaviors Inheiritance of acquired traits - longer legs, brighter feathers (Example: fiddler crabs, giraffes)

Darwin’s Friend Malthus Thomas Malthus - Economist Population Growth Resources are finite Not enough for everyone Life History Theory Or difference in life spans (clams vs. humans)

Question of the Day How does Darwin determine how ancestors are related between 2 species? He looks at homologous structures, early development of embryos

15-3 Darwin’s Case The Origin of Species. Book by Darwin Talked about all his findings Evolution has taken place for millions yrs Will continue in the future

Natural Variation Darwin said species are not perfect & unchanging Called NATURAL VARIATION (differences among individuals) Example - aquilegia, human skin color, etc.

Artificial Selection Selective Breeding Choosing the individuals unnaturally to yield best results or variation Example - Cross Breeding of Dogs

Natural Selection Evolution Darwin’s Theory of Evolution Struggle for Existence - makes individuals of species compete for life (food, living space, mates Survival of the Fittest - ability for individual to adapt & thrive in its environment

More Natural Selection Survival of the Fittest takes many forms: Not just biggest, fastest or strongest Can be BEHAVIORS: Smarter (Bigger Brain) Teamwork (working or living in families)

More Natural Selection Descent with Modification - species adapt to a NICHE different from ancestors Niche - The function an organism within a community or particular area within a habitat occupied by an organism. All Big Cats: Descended from common ancestor Made own niche

Evidence of Evolution How did Darwin know things were evolving? The Fossil Record - distribution of ancient life remains Geographic Distribution of Species - where in the world a species developed Homologous Body Structures - similar body parts of ancestors or similar species Early Development Characteristics - embryos & fertilized growth

Darwin’s Theory Summarized Individuals in nature are different (Natural Variation) Organisms in nature produce more offspring than can survive (Struggle for existence) Organisms compete for limited resources (Survival of Fittest) Individuals best suited for environment will be most successful (natural selection) Species evolve over time & from common ancestors (Evolution, Common Descent & Descent w/ Modification)

Final Thoughts on Evolution Where is the future of evolution headed? Was Darwin right? Could there be Devolution? I say no because of all the scientific evidence But You need to make up your mind