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Darwin Returns to England

Darwin Returns to England. The Beagle returned to England in 1836. Scientists were astonished at the great variety of unknown organisms. Many island species looked similar yet different from mainland species. a mainland finch. 1 of the Galapagos finches. Darwin’s Delay in Publishing.

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Darwin Returns to England

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  1. Darwin Returns to England The Beagle returned to England in 1836. Scientists were astonished at the great variety of unknown organisms. Many island species looked similar yet different from mainland species. a mainland finch 1 of the Galapagos finches

  2. Darwin’s Delay in Publishing Darwin delayed publishing his ideas due to concerns for how they would be accepted. Darwin finally decided to publish in 1859 after receiving a letter from Alfred Russel Wallace outlining the same theory. Alfred Russel Wallace

  3. Darwin Presents his Theory Later that year, Darwin presented his ideas, along with Wallace’s, at a scientific meeting.

  4. The Origin of Species Within a year (1859), Darwin published his book on evolution, On the Origin of Species by Means of Natural Selection.

  5. Ideas within Darwin’s Theory Genetic Variation Darwin stressed that there is a great amount of “genetic variation” within a species – he called this “heritable variation”. 4 varieties of the same species

  6. Ideas within Darwin’s Theory Artificial Selection Darwin noticed that humans had been shaping organisms to have desired traits for hundreds of years.

  7. Ideas within Darwin’s Theory Struggle for Existence From Malthus, Darwin realized that more offspring are often born than what the recourses can support.

  8. Ideas within Darwin’s Theory Survival of the Fittest Darwin saw that organisms had adaptations for surviving in their environment. He also saw that some members of a species had better fitness (ability to survive) than others. Adaptation – any trait that increases the chance for survival Fitness – how well an organism is adapted to an environment

  9. Ideas within Darwin’s Theory Survival of the Fittest Darwin realized that all members of a species do not have the same fitness because of their heritable variation and other factors.

  10. Ideas within Darwin’s Theory Natural Selection Darwin summarized that over time, nature (the organism’s environment) determined whether an individual was fit enough to survive. Nature was selecting which survived.

  11. Ideas within Darwin’s Theory Natural Selection Those that survive will pass their adaptations on to their offspring.

  12. Ideas within Darwin’s Theory Descent with Modification Darwin said that species descend, with changes, from previous species over time. This principle is referred to as “common descent”.

  13. Ideas within Darwin’s Theory Descent with Modification The idea of organisms descending from common ancestors is often referred to as a “tree of life”.

  14. Evidence for Darwin’s Theory Evidence supporting Darwin’s theory of evolution comes from 4 sources. 1. fossils 2. geological distribution of living species 3. homologous structures of living things 4. embryology

  15. Evidence for Darwin’s Theory Fossil Evidence Many fossils have been found for organisms that are not live today.

  16. Evidence for Darwin’s Theory Fossil Evidence Many of the fossils are transitional species leading to modern species. Gaps in the fossil record are getting smaller.

  17. Evidence for Darwin’s Theory Geological Distribution of Living Species South American Tortoise Galapagos Tortoise Similar species separated by geographic barriers adapted to different habitats. Oregon Phoebe Nebraska Phoebe

  18. Evidence for Darwin’s Theory Geological Distribution of Living Species American Beaver South American Capybara Animals living in similar habitats on different continents often have similar adaptations.

  19. Evidence for Darwin’s Theory Homologous Structures Structures that are homologous develop from the same embryonic tissue but may have different shapes and functions.

  20. Evidence for Darwin’s Theory Vestigial Organs blind salamander appendix Body structures that are no longer needed/used have a tendency to disappear – these are called vestigial organs.

  21. Evidence for Darwin’s Theory Embryological Evidence Embryos of the vertebrates are very similar implying a common ancestor. next slide

  22. Summary of Darwin’s Theory Genetic Variation Members of a species have differences. Struggle for Existence More offspring are produced than can survive. Survival of the Fittest There is a competition for resources. Natural Selection Nature selects the most fit to survive and reproduce. Descent with Modification Living species descended from a common ancestor.

  23. Grand Unifying Theory of Biology The theory of evolution has helped advance our understanding of all areas of biology.

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