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Microevolution and Charles Darwin

Microevolution and Charles Darwin. son of a famous English Physician - a Noblemen was a Naturalist by hobby - collected specimens of nature did not like Medical School got his college degree in Theology in his 20’s took a job as a naturalist aboard the Beagle

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Microevolution and Charles Darwin

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  1. Microevolution and Charles Darwin • son of a famous English Physician - a Noblemen • was a Naturalist by hobby - collected specimens of nature • did not like Medical School • got his college degree in Theology • in his 20’s took a job as a naturalist aboard the Beagle • his biology teacher got him the job • sailed around the world for five years collecting specimens • based on his findings he introduced Natural Selection as the means of species evolution

  2. Artificial Selection: Animal Data Darwin had practiced Artificial Selection in Pigeons by breeding them for specific traits

  3. Artificial Selection: Plant Data Darwin had seen the effects of Artificial Selection in plant products by breeding them for specific traits

  4. Comparative Anatomical Data The forelimbs of all mammals have the same skeletal elements

  5. Comparative Embryological Data Identifies anatomical homology that is less apparent in adults

  6. Geological Data 1830: Lyell publishes Principles of Geology

  7. Fossil Data It is believed that whales evolved from terrestrial creatures. These fossils from Egypt and Pakistan show an extinct whale (Brachiosaurus) that had hind limbs. Transitional fossils link the past with the present

  8. “Living Fossil” Data Horseshoe Crabs are an example of a “living fossil” They have evolved very little over the last 600 million years.

  9. South American Data Darwin sails around the world and in South America is puzzled by the absence of rabbits. Instead he finds these rabbit-like Patagonian Hares or Mara (Dolichotis patagonum) that are not rabbits but have similar characteristics as rabbits. He postulates that they must have evolved just like rabbits because of their similar environments

  10. Galapagos Data Darwin sailed next to the Galapagos Islands, a set of islands 3000 miles away from any other land source. He carefully characterized the island finches based on their specific traits. He found that several different types of birds existed and each had specific traits that would allow them access to a specific food source on the island.

  11. Darwin’s Logic on Natural Selection • Any population has the capacity to produce more individuals than it can support. • If the natural resources are limited this will create a competition for those resources. • Variations in physical traits could give some individuals an advantage in the competition. • This advantage would increase the individual’s survival and reproduction chances. • These physical traits would then be passed on to the individual’s offspring via natural selection. • In this way populations evolve, not individuals.

  12. Evolutionary Timeline Summary • 10-20 bya: Galaxy forms • 5 bya: Earth forms • 4 bya: Life forms from non-life • 3 bya: Cyanobacteria evolve photosynthesis • 500 mya: Explosion of Life - Massive Extinction • 150 mya: Dinosaurs evolve • 66 mya: Dinosaurs become extinct • 5 mya: Humans begin to evolve • 50 tya: Neanderthals/Cro-Magnon • 10 tya: Homo sapians sapians

  13. Evolution of Nervous Systems • radial nerve • nerve net • segmental nerve • ganglion • nervous system

  14. Dinosaur Extinction? • Crater found • Dated to dinosaur extinctions • 66 million years ago • Iridium • Would we have evolved if this didn’t happen?

  15. Humble Beginnings?

  16. The Human Lineage

  17. Vertebrate Brain Evolution • midbrain emphasis decreases • forebrain emphasis increases • cerebellar emphasis increases

  18. Human Evolution and Brain Size Increases

  19. Varied Cortical Commitment Association Areas Increase with Evolution

  20. Varied Cortical Surface Area

  21. Genetics and Evolution Modern Day Chimpanzee Modern Day Human

  22. Evolution of Language Chimpanzee Human High in throat Low in throat • A random mutation causes the larynx to drop in human ancestor • This increases the complexity of sounds that the species could make • Couple this with a more complex brain and we have the advent of language • And the evolution of the species based on cognition and language

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