Understanding Evolution
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- Charles Darwin was a British naturalist who developed the theory of evolution by natural selection. He observed species on the Galapagos Islands and noticed finches with different beak shapes that corresponded to their habitats and food sources. - Influenced by Thomas Malthus' ideas about population growth, Darwin proposed that species evolve over generations through natural selection, where individuals with traits better suited to their environment tend to survive and pass on those traits. - Darwin spent over 20 years researching and developing his theory before publishing On the Origin of Species in 1859. He provided extensive evidence from his observations and from fossils that species have changed over time, leading to biodiversity. His theory of evolution by natural selection became the
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Understanding Evolution
- 1. EVOLUTION
- 2. Charles Robert Darwin Charles Darwin was born in England on February 12, 1809 After graduating from the best school at Shrewsbury in 1825, Darwin went to the University of Edinburgh to study medicine. In 1827 he dropped out of medical school and entered the University of Cambridge.
- 3. Charles Robert Darwin Darwin was an avid collector of beetles while at Cambridge
- 5. Charles Robert Darwin In 1831, he joined a 5 year scientific expedition on the survey ship HMS Beagle as their geologist.
- 6. Charles Robert Darwin The idea of evolution has been around for a long time (even before Darwin)
- 7. Charles Robert Darwin Darwin read a book called “Principles of Geology” by Charles Lyell on the Beagle
- 8. Charles Robert Darwin Lyell suggested that the fossils found in rocks were actually evidence of animals that had lived many thousands or millions of years ago. Lyell's argument was reinforced in Darwin's own mind by the rich variety of animal life and the geological features he saw during his voyage.
- 9. Charles Robert Darwin Darwin noticed that each island supported its own form of finch which were closely related but differed in important ways.
- 10. Charles Robert Darwin Darwin found that the shapes of tortoise shells corresponded to different habitats.
- 12. Charles Robert Darwin Another scholar of the time, Thomas Malthus, studied populations and had a great impact on Darwin’s understanding of finches, other organisms, and his theory of evolution. Malthus believed that given unlimited resources, a population would grow exponentially. Under normal conditions, a natural population would be limited by food, water, habitat, etc. resulting in a balancing of population numbers. Influenced by the ideas of Malthus, Darwin proposed a theory of evolution occurring by the process of natural selection.
- 14. Charles Robert Darwin Survival of the fittest The animals (or plants) best suited to their environment are more likely to survive and reproduce, passing on the characteristics which helped them survive to their offspring. Gradually, the species changes over time.
- 15. Charles Robert Darwin Darwin worked on his theory for 20 years. After learning that another naturalist, Alfred Russel Wallace had developed similar ideas the two made a joint announcement of their discovery in 1858.
- 16. Charles Robert Darwin In 1859 Darwin published : ‘ The Origin of Species ‘ by Means of Natural Selection
- 17. Evolution Change over time Occurs to species, not individual Explains diversity on Earth today Great variety of types of living things Between species 10 – 100 million species on earth How Evolution Works : Explained by Charles Darwin and Alfred Russell Wallace Darwin wrote On the Origin of Species
- 19. How Evolution Works 1. Overpopulation • more individuals born than can survive
- 20. How Evolution Works 2. Competition • for limited resources some will survive
- 21. How Evolution Works 3. Variation • Differences among individuals a result of genetic mutation – changes in DNA
- 22. How Evolution Works 4. Adaptation some variation gives some individuals a slight survival advantage these are favorable traits traits or characteristics that help an organism survive in its ecosystem three types:
- 23. How Evolution Works 1.Structural and Behavioral : Physical structure that helps organism survive
- 24. How Evolution Works 2. Chemical Chemical that helps organism survive Octopus Skunk
- 25. How Evolution Works 3.Camouflage Allows an organism to blend with its environment Owl Frog
- 26. Charles Darwin predicted: Darwin's Comet Orchid
- 27. The Forces of Evolution Genetic Drift Genetic Recombination Mutation Gene Flow Natural selection
- 28. The Forces of Evolution
- 29. Genetic Drift A population bottleneck : is a sharp reduction in the size of a population due to environmental events such as: (earthquakes, floods, fires, disease, or droughts)
- 30. Genetic Drift B Founder effect : is the loss of genetic variation that occurs when a new population is formed by a very small number of individuals from a larger population It was first fully outlined by Ernst Mayr in 1942
- 32. Mutation
- 33. Gene Flow
- 34. Natural Selection That results in the adaptation of an organism to its environment Determines the traits that allow organism to multiply and survive Evolution often occurs as a result of this process
- 35. Evidences of Evolution The Fossil Record Comparative anatomy Embryonic Development Vestigial organs Molecular biology
- 39. Vestigial Organs Wisdom Teeth Third Eyelid Darwin’s Point Coccyx Appendix Goose Bumps Jacobson’s Organ Junk DNA Extra Ear Muscles Plantaris muscle
- 40. Molecular biology Universal Codon Code Pseudogenes Vitamin C Human Chromosome 2 Endogenous retroviruses (ERVs)
- 45. Types of Evolution Divergent Evolution • Organisms have a common ancestor • Changes in environment cause them to adapt • So they may look/ act differently, but they are still related!
- 46. Types of Evolution Convergent Evolution • Organisms have similar features • However, they don’t have a common ancestor! • So they may look/ act the same, but they are not related!
- 47. Types of Evolution Convergent Evolution • Organisms have similar features • However, they don’t have a common ancestor! • So they may look/ act the same, but they are not related!
- 48. Speciation The most widely accepted definition: A species is a group of individuals capable of interbreeding to produce fertile offspring it has a problem : Hybrid Infertility Horse X Donkey = Mule (Cannot Reproduce and produce Fertile offspring)
- 49. Speciation So a better definition of a species might be: A group of individuals capable of interbreeding to produce offspring that are fertile and these offspring, in turn, can produce offspring that are fertile. The process by which new species develop from the existing species is known as : Speciation.
- 50. Speciation
- 51. Speciation
- 52. Evolution Microevolution: • genetic change in a population from one generation to the next Macroevolution: • Processes through which new species arise
- 53. Microevolution Moths : • At the beginning of the Industrial Revolution in England, coal burning produced soot that covered the countryside in many areas
- 54. Microevolution • What do you think happened?
- 55. Microevolution White moths became easier to see, while the black moths became harder to see. The black moths were more likely to survive and pass on the gene for dark color to their offspring Over time, the black moths have become more common
- 56. Macroevolution • Transitional Fossils : Prominent examples: Archaeopteryx Tiktaalik Darwinius masillae Ardipithecus ramidus Australopithecus afarensis
- 57. Macroevolution Archaeopteryx : Origin of birds Temporal range: Late Jurassic, 150.8–148.5 Ma
- 58. Macroevolution Tiktaalik roseae : Fish to Reptile Temporal range: Late Devonian, 375 Ma
- 60. Macroevolution Darwinius masillae : Origin of Primates Temporal range: Middle Eocene, 47 Ma
- 61. Macroevolution Ardipithecus ramidus : Apes to humans 4.4 Ma
- 62. Macroevolution Australopithecus afarensis: Apes to humans 2.9_3.9 Ma