evolution is defined as gradual change over time time being one critical element of the definition

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  • Evolution is defined as gradual change over time Time being one critical element of the definition.
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  • Jean Baptiste Lamarck Author of first systematic theory of evolution Theory on the evolution of acquired characteristics Believed that modifications of form due to environmental circumstances
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  • Lamarcks Theory Use it or lose it Internal drive toward complexity caused inheritance of acquired characteristics The giraffes neck is the classic example
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  • Lamarcks theory At some point in the past, giraffes found themselves in an environment where they had difficulty reaching food on the tops of tree. They had to stretch their necks and in doing so, physically lengthened them. This longer neck was passed on to the next generation, who stretched even further, resulting over time in giraffes having long necks.
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  • Lamarcks Theory of Evolution Inheritance Of Acquired Traits Traits Acquired During Ones Lifetime Would Be Passed To Offspring Clipped ears of dogs could be passed to offspring!
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  • Lamarcks Theory of Evolution Tendency Toward Perfection Organisms Are Continually Changing and Acquiring Features That Help Them Live More Successfully In Their Environment Example: Bird Ancestors Desired To Fly So They Tried Until Wings Developed
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  • Lamarcks Mistakes Lamarck Did NOT Know how traits were inherited (Traits are passed through genes) Genes Are NOT Changed By Activities In Life Change Through Mutation Occurs Before An Organism Is Born
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  • Charles Darwin the Naturalist
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  • Charles Darwin The Author of the On the Origin of Species The most notable evolution theorist of our time Known for his famous voyage on The Beagle
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  • Charles Darwin Born in England Wealthy, sophisticated English family 1827 dropped out of medical school & entered Cambridge to prep for the clergy Became a meticulous observer of natural phenomena & collector of specimens at 22 was taken aboard HMS Beagle as a naturalist on a scientific expedition around the world Arrived at the Galapagos Islands on September 15 th, 1835 5 week stay was on land 19 days collecting & observing
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  • In 1831, the young naturalist Charles Darwin set off on a five-year sail around the world that would profoundly change not just his life, but the course of science as well. Commissioned to collect samples of flora and fauna from the HMS Beagles ports of call, Darwin left England firmly believing, like everyone else, that God had created every living thing on Earth exactly as it appeared. His specimens told him otherwise, however, and when the Beagle docked in England, core tenets of the theory of evolution had been shaped. Yet it would be 20 years before he would make his ideas public; Darwin feared that disclosing his radical views would be the equivalent of committing career suicide and was moved to publish only when another scientist independently arrived at the same conclusions as he. That event sparked a debate that continues to this day.
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  • Charles Darwin In 1831 he sailed to the Galapagos Islands in the HMS Beagle He left England on this voyage at 22 yrs. Old He published his theory of evolution 30 years later
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  • Darwin Left England in 1831 Darwin returned 5 years later in 1836
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  • 13 major islands, 6 minor islands, & 40 smaller rock formations & reefs 3000 square miles of land covering 17,000 miles of ocean located 600 miles west of Ecuador
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  • Galapagos Islands Volcanic in origin oldest are 325 million years old Hot spot formation theory Still active volcanoes Never connected to the mainlands
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  • Galapagos Islands Until their discovery in 1535, life here evolved in isolation producing strange & marvelous species 8 Habitats to accommodate a large variety of species: Open seaRocky islets Rocky shoresSandy beaches Mangrove coastsArid zone Transitional zoneHighlands
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  • Bartolome Island arid zone
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  • North Seymour Island transition zone
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  • Rocky Islets Black Sand Beach
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  • Flamingos on the mangrove coasts
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  • Rocky shores Red Sand Beach
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  • Highlands View atop a inactive volcano
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  • Darwin and the Galapagos He focused evolutionary principles on populations Why were there so many different plants and animals found in the Galapagos?
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  • Animals of Galapagos Galapagos Penguins Land Iguana Pink Flamingo
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  • Frigate Bird
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  • Galapagos Tortoise There are currently only 11 subspecies Left in the world today. Tortoise nesting video
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  • Lonesome George George is a Pinta Island Tortoise He is the very LAST one known in existence There is a reward of $10,000 offered by the zoo association if a female is found
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  • Charles Darwin Research Center International, nonprofit organization for scientific research, environmental education & conservation Founded in 1959 Captive breeding program for endangered giant tortoises & land iguanas
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  • The Boobys Blue Footed booby Red footed booby Masked booby
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  • Blue Footed Booby http://www.youtube.co m/watch?v=oYmzdvM oUUAhttp://www.youtube.co m/watch?v=oYmzdvM oUUA Mating Dance
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  • Waved Albatross
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  • Animals of the Galapagos Marine iguana Sally Lightfoot Crabs Sea Lions
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  • Darwins Ideas Evolution is due to genetic variation and natural selection on heritable characters Recognized natural selection as the mechanism in 1838 Darwin at 31 Sketch of genetic line
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  • Darwins 5 Major Theories 1. The organisms steadily evolve over time (evolution theory) 2. Different kinds of organisms descended from a common ancestor (common descent theory) 3. Species multiply over time (speciation theory) 4. Evolution takes place through the gradual change of populations (gradualism theory) 5. The mechanism of evolution is the competition among vast numbers of unique individuals for limited resources under selective pressures, which leads to differences in survival and reproduction (natural selection theory)
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  • Weaknesses in Darwins natural selection theory 1. Blending inheritance was favoured rather than discrete Mendelian genes (which was unknown at the time) 2. No knowledge of Mendelian genetics was available 3. Phyletic gradualism was favoured as the type of speciation 4. Fecundity (fertility) was not emphasized in the description of fitness 5. Sexual selection: Sexually selected characters were seen as ornaments but they may be advertising genuine male qualities (Hamilton & Zuk, 1982)
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  • Evidence used in Darwins Natural Selection Theory 1. Biogeography: Distinct features of cosmopolitan species and the presence of endemic species (Darwin's finches: of the 14 finch species of the Galapagos islands, 13 are endemic) 2. Morphology and embryology: Homologous structures among related species; similarities in the embryos of related species Homologous Structure-features that are similar in structure but appear in different organisms and have different functions; offers support for common ancestor Analogous Structure-perform a similar function but are not similar in orgin 3. Palaeontology: Gradual change in the fossil record, evident extinctions 4. Taxonomy and systematics: Morphological similarities among related taxa
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  • Vestigial Structures
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  • Compare Lamarck & Darwin LamarckDarwin Concept of Species Population all same (identical characteristics) capable of transformation during lifetime Population w/similar characteristics, variation common depending on environment. No transformation in lifetime, only through genetic means Mechanism of new species Modified during life & then inherited by offspring. Change directed to meet survival Natural Selection. Variation exists regardless of organisms' needs. Those most fit survive & reproduce ExampleGiraffes neck, fiddler crabGalapagos finch, eyesight of the hawk Potential ProofAdaptationsAdaptations, fossil records, homologous structures, biogeographical diversity patterns
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  • Natural Selection Darwin is credited with the theory of evolution by natural selection. Natural selection is that the strongest survive and propagate and therefore increase the strength of the species Survival of the Fittest Fitness-an organisms ability to survive & reproduce
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  • Darwin Finches Once on the islands, various s


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