Understanding the Diversity of Life Part 2 - PowerPoint PPT Presentation

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Understanding the Diversity of Life Part 2

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  1. Understanding the Diversity of LifePart 2 EVOLUTION & SPECIATION 1

  2. MODERN EVOLUTIONARY THEORY • By combining the work of Charles Darwin with modern genetics, evolutionary biologists have a much better understanding of how evolution works

  3. MODERN EVOLUTIONARY THEORY • What is a population? • What is a gene pool? • Group of individuals of the same species that interbreed • All of the genes that a population has in common

  4. MODERN EVOLUTIONARY THEORY • What is relative frequency? • In genetic terms, evolution is… • How often an allele occurs in a gene pool • any change in relative frequency of alleles in a population

  5. MODERN EVOLUTIONARY THEORY • What are the 2 main sources of genetic variation • Mutations • Gene Shuffling

  6. MODERN EVOLUTIONARY THEORY • What is a mutation ? • Why does a mutation occur? • Change in DNA sequence • Mistakes in replication • Exposure to radiation • Chemicals in the environment

  7. MODERN EVOLUTIONARY THEORY • What is gene shuffling? • What happens during gene shuffling? • Distribution of different alleles during meiosis • Each new gamete gets a different set of alleles

  8. BEYOND MUTATIONS & GENE SHUFFLING • Non-random mating is… • Examples: • Results: • Some members of the population have more opportunity to mate than others • Fighting (lions & walrus) • Dances/songs (birds) • Better fighters/dancers mate with more females

  9. BEYOND MUTATIONS & GENE SHUFFLING • Gene flow is… • Gene flow has… • Why? • Gain or loss of genes as organisms move in and out of populations • Less effect on large populations • Genes are diluted by large pool

  10. BEYOND MUTATIONS & GENE SHUFFLING • Genetic Drift is… • Occurs more often in… • Why? • Random change in allele frequency causes an allele to become more common • Small populations • Fewer alleles to counteract affects

  11. BEYOND MUTATIONS & GENE SHUFFLING • Types of genetic drift: • Bottleneck effect – happens due to… Examples: • Catastrophic events • Random survivors whose genes do not reflect original population • Bald Eagle • American Bison

  12. BEYOND MUTATIONS & GENE SHUFFLING 1963 – 417 mating pairs DDT Buildup 1890’s – 750 animals Overhunting

  13. BEYOND MUTATIONS & GENE SHUFFLING • Types of genetic drift: • Founder effect - happens when… Examples: • A few organisms from a larger population are transferred to another location • Darwin’s Finches • Seeds carried by wind/water

  14. SPECIATION

  15. SPECIATION • What is a species? • What is speciation? • A group of organisms capable of interbreeding and producing fertile offspring • A change in organisms that leads to new species

  16. SPECIATION • How does speciation happen? • Organisms from a population must be reproductively isolated from each other

  17. SPECIATION • Geographic isolation leads to speciation because… • Examples: • It puts a physical barrier between members of a population • Earthquakes • Mountain ranges • Human activity

  18. SPECIATION • Behavioral isolation leads to speciation because… • Geographically isolated members of a population develop new mating behaviors

  19. SPECIATION • Temporal isolation leads to speciation because… • Members of a population start to reproduce at different times

  20. PATTERNS OF EVOLUTION

  21. MACROEVOLUTION • What is macroevolution? • Large-scale history of life on earth

  22. MACROEVOLUTION 1. Extinction is… • Extinction happens because… • The complete loss of a species from Earth • Organisms are unable to adapt to changes in the environment

  23. MACROEVOLUTION 2. Adaptive radiation is… • Adaptive radiation happens when… • Example: • Evolution of one species into several species • A species moves into a new, unoccupied region • Darwin’s Finches

  24. MACROEVOLUTION 3. Coevolution is… • Examples: • The evolution of 2 different species due to their interactions with each other • Mutualism • Predator-Prey • Parasitism

  25. MACROEVOLUTION 4. Convergent evolution is… • These structures are called… • Convergent evolution happens because… • The development of body structures with similar functions that are structurally different • Analogous structures • Vastly different organisms face similar environmental demands

  26. MACROEVOLUTION • Examples of convergent evolution in organisms: • Birds • Bats • Bugs

  27. MACROEVOLUTION 5. What are Hox genes? • Where are Hox genes found? • Why are Hox genes important? • A specific sequence of nucleotides about 180 units long • In the DNA of most animals • They are the master genes that control embryological development of body plans

  28. MACROEVOLUTION 6. Punctuated equilibrium is… • Punctuated equilibrium occurs after… • Example… • Rapid period of speciation between long periods of stability • A catastrophic event • Some sort of massive mutation occurs in a gene pool • Cambrian Explosion

  29. MACROEVOLUTION Catastrophic Event Massive Mutation in Gene Pool