Since Darwin s work, every scientific test has supported Darwin s basic ideas about evolution

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1 Guided Reading Answers Since Darwin s work, every scientific test has supported Darwin s basic ideas about evolution Biogeography Biogeography is the study of where organisms live now, and where they and their ancestors lived in the past Patters in the distribution of living and fossil species tell us how modern organisms evolved from their ancestors.

2 Closely Related but Different Over time, natural selection can produce variations among populations that resulted in different, but closely related species that are separated by some structure (like islands) Distantly Related but Similar Similar habitats around the world are home to distantly related animals and plants, but the similarities among those animals and plants provide evidence that similar selection pressures had caused distantly related species to develop similar adaptations.

3 Ch 16 Darwin s Theory of Evolution 16.4 Evidence for Evolution

4 Many scientist did not initially support Darwin s ideas about evolution Since his book was published, scientists have found evidence in many fields of science that support the theory New technologies and new ideas helped find this evidence

5 Biogeography Biogeography study of where organisms live now and where their ancestors lived in the past Scientists have found patterns in how living things and the fossils of their ancestors are distributed

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7 - Two biogeographical patterns: Closely Related but Different Closely related organisms may have developed different traits because of their separate location, but they share a close common ancestor Example: Finches on the Galapagos May have descended from a common ancestor on mainland South America, but became different species when they moved to different islands and developed different traits

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9 Distantly Related but Similar Organisms living in the same type of habitat may be distantly related, but they have developed similar traits Example: The Rhea, Emu, and Ostrich are not closely related, but because they live in similar habitats (grasslands), they have developed similar traits, such as long necks and legs

10 The Age of Earth and Fossils Age of the Earth Evolution needs millions of years to work Hutton and Lyell provided support for the idea that the Earth is billions of years old, giving enough time for evolution to have worked Radioactive dating has since supported Hutton and Lyell s ideas

11 Recent Fossil Finds Fossils are used as support for the idea that organisms change over time, by showing ancestors of current organisms Recently discovered fossils have connected current organisms with ancient ancestors by showing the intermediate steps in the organism s evolution Example: Fossils have been found to connect whales and dolphins to their land-dwelling ancestors

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13 Comparing Anatomy and Embryology Anatomy Homologous structures Structures that are shared by closely related species, but have changed in response to each species environment Shows a connection to a single ancestor and how that structure has changed over time Generally, the more similar the structures are, the more closely related those species are

14 Example: The hand of a human, cat, bat, and whale have the same bone structure, but the shape has changed in order to function best for each animal

15 Analogous structures Structures that are similar in structure and function, but do not share a common ancestor Developed in order to perform similar functions because the species live in a similar habitat

16 Example: A dolphin s fin is similar to a fish s fin, but they are not closely related A bird s wing is similar to a bat s wing, but they are not closely related

17 Vestigial Structures Structures found in an organism that was found in its ancestors, but no longer serves a particular function because of changes in the species over time

18 Example: Hip bones in whales and dolphins no longer needed for legs, but shows that ancestors did have legs

19 Human appendix remains from our ancestors that ate more vegetation, but not fully needed to day because of our changed diets Is still believed to have some minor function

20 Human wisdom teeth needed in our ancestors to replace teeth that were lost because of use. We no longer lose teeth as easily, so wisdom teeth are no longer needed

21 Vestigial structures are not quickly lost because they do not give the individual a disadvantage (natural selection doesn t cause them to be lost)

22 Embyrology Similarities in the way organisms embryos develop show connections between the species The development of chickens, rabbits and humans is very similar in the early stages The more closely related two species are, the more similar their embryological development will be Human and rabbit development will be more similar than human and chicken development

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24 Genetics and Molecular Biology The chemical make up of organisms can show how closely related two species are Universal Genetic Code All organisms use the same system of DNA, RNA and proteins Closely related species will have similar DNA sequences Similar Genes can also be found in closely related species

25 Homologous Molecules - Similar molecular structures can show how closely related species are A molecule called cytochrome c is very similar in many organisms

26 Tracing evolution using molecular data

27 How do we know evolution happens? Did humans evolve?