3Question for ThoughtEarth has millions of other kinds of organisms of everyimaginable shape, size, and habitat.This variety of living things is called biologicaldiversity. How did all these different organisms arise?How are they related?
4In your own words, describe what YOU think the theory of evolution means…
5Darwin’s Theory of Evolution Evolution refers to a change over time. Organic Evolution 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.
6What is a species? Populations in which genes are exchanged through interbreeding What is speciation?The process of developing new species.
7How do you think Darwin came up with his theory How do you think Darwin came up with his theory? (He did not “Google” it!)
8Ideas from other scientists that shaped Darwin’s Thinking James Hutton:1795 Theory of Geological changeCharles Lyell:Book: Principles of GeographyJean Baptist Lamarck: Tendency toward Perfection (Giraffe necks)
11Voyage of Beagle Dates: February 12th, 1831 Captain: Charles Darwin Ship: H.M.S. BeagleDestination: Voyage around the world.Findings: evidence to propose a revolutionary hypothesis about how life changes over time
13Patterns of DiversityDarwin 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.
14Patterns 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?
15Living Organisms and Fossils Darwin collected the preserved remains of ancient organisms, called fossils.Some of those fossils resembled organisms that were still alive today.
16Living 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?
18True FossilsThe remains of the dead animal or plant or the imprint left from the remains. Such as…bonesteethskin impressionshairthe hardened shell of an ancient invertebrateimpression of an animal or plant, even if the actual parts are missing.
19Trace Fossils…Something that was made by the animal while it was living that has hardened into stone. Such as…footprintsburrowscoprolite (animal poop)
20Other places to find ancient animal remains: Frozen glaciersAmberTar pits
21The Galapagos IslandThe smallest, lowest islands were hot, dry, and nearly barren-Hood Island-sparse vegetationThe higher islands had greater rainfall and a different assortment of plants and animals-Isabela- Island had rich vegetation.
22Animals found in the Galapagos Land TortoisesDarwin FinchesBlue-Footed BoobyMarine Iguanas
24The Galapagos IslandDarwin was fascinated in particular by the land tortoises and marine iguanas in the Galápagos.Giant tortoises varied in predictable ways from one island to another.The shape of a tortoise's shell could be used to identify which island a particular tortoise inhabited.
27The Journey HomeDarwin Observed that characteristics of many plants and animals vary greatly among the islandsHypothesis: Separate species may have arose from an original ancestor
28The Origin of SpeciesDarwin publish his findings in 1859.
29Natural & Artificial Selection Natural variation--differences among individuals of a speciesArtificial selection- nature provides the variation among different organisms, and humans select those variations they find useful.
30Evolution by Natural Selection The Struggle for Existence-members of each species have to compete for food, shelter, other life necessitiesSurvival of the Fittest-Some individuals better suited for the environment
31Struggle For Existence & Survival of The Fittest
32Natural SelectionOver time, natural selection results in changes in inherited characteristics of a population. These changes increase a species fitness in its environment.
33DescentDescent with Modification-Each living organism has descended, with changes from other species over timeCommon Descent- organisms today were derived from common ancestors
34Evidence of Evolution The Fossil Record Geographic Distribution of Living ThingsHomologous Body StructuresSimilarities in Early Development
35Evidence for Evolution The Fossil Record-Layers show changeGeographic Distribution of Living ThingsHomologous Body StructuresSimilarities in Early Development
36Evidence of Evolution The Fossil Record Geographic Distribution of Living Things-similar environments have similar types of organismsHomologous Body StructuresSimilarities in Early Development
37Homologous Structures Homologous Structures-structures that have different mature forms in different organisms, but develop from the same embryonic tissue
43Molecular BiologyRecent science has been able to study the genetic blueprint of organisms. Similarities in DNA may show relationships to common ancestors.
44Summary of Darwin’s Theory… Individuals in nature differ from one another.Organisms in nature produce more offspring than can survive, and many of those who do not survive do not reproduce.
45Summary of Darwin’s Theory Because more organisms are produced than can survive, each species must struggle for resources.Each organism is unique, each has advantages and disadvantages in the struggle for existence.
46Summary (cont.)Individuals best suited for the environment survive and reproduce most successfully.Species change over long periods of time.
47Summary (cont.)Species alive today descended with modification from species that lived in the past.All organisms on earth are united into a single family tree of life by common descent.
48The evolutionary relationship among species. PhylogenyThe evolutionary relationship among species.Utilizes tree-like diagrams to show evolutionary lines of descent.