Ch. 15: Evolution - change in a species or the formation of new species over time

Transcription

1 Ch. 15: Evolution - change in a species or the formation of new species over time

2 15.1 Darwin

3 Early Beliefs All species permanent and unchanging Earth only a few thousand years old religion Beliefs based on

4 Georges Cuvier Found evidence that: Ancient organisms very different Some stopped existing: Extinction Catastrophism sudden geological events caused extinction

5 Charles Lyell Geologist Uniformitarianism : Earth's surface has been changed by geological processes ex: earthquakes, volcanic eruptions

6 Thomas Malthius Economist Stated that: 1. Nature over produces offspring 2. Overpopulation could destroy the earth 3. Forces that prevent overpopulation: a. Disease b. Starvation c. War

7 Jean Baptiste Lamarck Believed in evolution His explanation of how evolution occurred : wrong was Inheritance of acquired characteristics Traits acquired during life passed to offspring ex: passing big muscles on to offspring

8 Charles Darwin 1830's Famous evolutionary biologist Described evolution as Descent with Modification - new species descend from pre-existing species ex: Galapagos Finches (13 species) from 1 ancestor

9 Darwin's Finches

10 How does evolution occur? Natural Selection 1. Overproduction: - species over produce young 2. Genetic Variation: - some organisms inherit traits which improve/harm survival: - ex: strength, disease resistance

11 3. Struggle to Survive - organisms compete to survive/mate - some have Adaptations: trait that makes individual more likely to survive & mate

12 4. Differential Reproduction - those w/ best adaptations survive & reproduce - trait passed on to offspring - population changes as traits become more common - shows Fitness: measure of individual's genetic contribution to next generation

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14 Peppered Moths: Natural Selection at work

15 15.2 Evidence of Evolution

16 Evidence of Evolution Fossils Remains or traces of organisms that lived long ago Best evidence of evolution: shows life has changed often found in rock strata (layers)

17 Principle of Superposition Proposed by Nicholas Steno In undisturbed rock layers, oldest layer is on bottom; newer layers on top

18 Transitional Species have features between ancestors and descendants ex: whales: ancestor was 4 legged

19 Transitional Whale Species

20 Anatomical Evidence 1. Homologous Structures: similar anatomy in different species Indicates a common ancestor Human, penguins, alligators & bats have forelimbs w/ homologous bones

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22 2. Analogous Structures Structures with similar functions DO NOT come from common ancestor Bats, birds & moths all have wings, but wings have different parts evolved separately

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24 3. Vestigial Structures Serve no function but resemble functional structures in related organisms ex: human s tailbone, whale s pelvis

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26 Embryological Evidence At certain stages, developing embryos look a lot alike Indicates evolutionary relationships The longer embryos look alike, the closer the organisms are related

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28 Molecular Evidence Similarities in DNA, RNA, & proteins indicate evolutionary relationship More similarities = closer relationship Human & Chimp DNA is 96% identical!

29 15.3 Evolutionary Patterns

30 Patterns of Evolution 1. Convergent Evolution Different species evolve similar traits as they adapt to same kind of environment Causes Analogous structures to form ex: evolution of wings for flight

31 Convergent Evolution

32 2. Divergent Evolution Descendants of common ancestor become more different as each adapts to own environment Causes Homologous structures to form ex: anole lizards

33 Divergent evolution

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36 3. Adaptive Radiation Happens to a population in new environment rapid divergent evolution until population fills all parts of environment ex: Darwin's Finches: 13 species from 1 ancestor

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38 4. Co-evolution 2 or more species evolved together Can be beneficial to each species ex: flowers & their pollinators

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40 5. Artificial Selection Divergent evolution caused by humans Selective breeding: choosing best organisms to breed ex: human caused dogs to evolve from wolves15,000 years ago 1 species to 600 subspecies

41 Resistance Bacteria have evolved to become resistant to antibiotics Divergent evolution Due to misuse & incorrect use of antibiotics Creates superbugs : ex: MRSA