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Exploring Evolution: The Story of Darwin and Natural Selection

Dive into the world of evolution through the eyes of Darwin and the concept of natural selection. Explore how life changes over time in response to the environment, influenced by scientists like Lamarck. Discover various evidences for evolution, including fossils, comparative anatomy, comparative embryology, biochemistry, and genetic evidence. Learn about adaptations that help species thrive and survive. Unveil the mechanisms of evolution, from species formation in populations to the shifting gene pools. Challenge common misconceptions and embrace the fascinating journey of evolution.

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Exploring Evolution: The Story of Darwin and Natural Selection

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  1. Evolution

  2. Evolution Evolution- change in population over time

  3. Evolution- Darwin Darwin • father of modern evolutionary theory • Galapagos Islands • HMS Beagle

  4. Darwin HMS Beagle • Trip around the world

  5. Scientists who influenced Darwin • Lamarck- organisms change due to the pressures of their environment, traits are acquired • He proposed that by using or not using its body parts, an individual tends todevelopcertaincharacteristics, which itpasseson to itsoffspring.

  6. Scientists who influenced Darwin- Lamarck • Example: A giraffe acquired its long neck because its ancestor stretched higher and higher into the trees to reach leaves, and that the animal’s increasingly lengthened neck was passed on to its offspring.

  7. Natural Selection • Natural Selection- organisms with traits best suited to the environment survive • have more offspring

  8. Natural Selection • Example: Peppered Moths during the Industrial Revolution

  9. Natural Selection Extinction- permanent loss of a species 5 mass extinctions throughout history

  10. Evidence for Evolution • 1. Fossils • 2. Comparative anatomy • 3. Comparative embryology • 4. Biochemistry • 5. Genetic evidence • 6. Direct evidence

  11. Evidence for Evolution 1.Fossils • mold or cast of organism left in rock, fossilized bone and teeth • life becomes more complex over time • record is incomplete

  12. Evidence for Evolution • Most complete fossil record is for the horse

  13. Evidence for Evolution Relative dating- • layers in rock bed used to date organisms • Deeper is older, shallow is younger

  14. Evidence for Evolution • Radioisotope dating- uses half-life of element to estimate age of organism Carbon is used frequently

  15. Evidence for Evolution • phylogeny- description of the lines of descent of plants and animals as they lived from one to the next (how they are related)

  16. Evidence for Evolution 2.Comparative Anatomy- the study of the structures of different organisms homologous parts modified structures among different groups of descendants

  17. Evidence for EvolutionComparative Anatomy

  18. Evidence for EvolutionComparative Anatomy • analogous parts-structures in organisms that have no common origin but serve the same function • Example: bird’s wing, bat’s wing and insect’s wing

  19. Evidence for EvolutionComparative Anatomy • vestigial organs- organs having no functions in the living organism Vestigial toes in the horse Vestigial pelvis and femur in whales

  20. Evidence for Evolution 3.Comparative Embryology the study of developing plants and animals Below is the pictures of embryos for a fish, human, rabbit, tortoise, and chicken. Can you guess which one is each type of organism? 1 2 3 4 5

  21. Evidence for Evolution • Comparative Embryology Here the pictures of the second set of development is added. Can you tell now? 1 2 3 4 5

  22. Evidence for Evolution • How about now? 1 2 3 4 5

  23. Evidence for EvolutionComparative Embryology- The complete picture

  24. Evidence for Evolution • 4. Biochemistry • comparison of DNA and proteins in the body • Example: comparison of hemoglobin (blood protein) in human, chimp, and dog. Human and chimp hemoglobin more alike than dog

  25. Evidence for Evolution • The closer related the fewer differences in DNA and proteins

  26. Evidence for Evolution • 5.Genetic Evidence • Mutations- mistakes in the genetic code • Causes changes in populations over time

  27. Evidence for Evolution • 6. Direct Evidence • Rapid Evolution • Strains of bacteria becoming resistant to antibiotics • Weeds and pesticides • Insects and pesticide

  28. Adaptations • Adaptation- change in a species that makes it better suited to its environment A hump to store nutrition during long trips or when food or water is scarce Fur inside the ears to protect inner ear from sand Long eyelashes to protect their eyes from the sand when the wind is blowing Nostrils that close to keep sand out Calluses on the the knees to protect from abrasion Large feet for standing in the sand

  29. Types of Adaptations Structural • Changes in structure or anatomy • Example: bird’s beak or claws • Mimicry- a harmless species resembles a harmful one, predators learn to avoid both species • Camouflage- species features blend in with the environment

  30. Mimicry

  31. Camouflage

  32. Types of Adaptations Physiological • Changes in chemical makeup • Examples: digestion enzymes, snake venom, octopus ink

  33. Types of Adaptations • Behavioral • Responses to the environment • Example: bird migration

  34. Mechanisms for Evolution • Species- group of organisms that can interbreed AND produce viable offspring • Populations evolve NOT individuals

  35. Origin of a Species Common Misperception: • Individuals Evolve Species evolve NOT individuals “And now there go the Wilsons!... Seems Like everyone’s evolving except us!”

  36. Mechanisms for Evolution • Gene pool- all the alleles for a trait in the population • Over time gene pools shift to traits that are best suited to the environment • Allelic frequency- the percent of any specific gene in a population • Genetic Equilibrium- when the percentage of alleles in a population remains stable over time

  37. Natural Selection acts on variation in a population • 1.stabilizing – favors average individual • 2.directional – favors one extreme variation • 3.disruptive – favors both extremes of variation

  38. Natural Selection acts on variation in a population

  39. Origin of Life on Earth • Spontaneous generation- non-living materials can produce life, life could be created out of nothing, from the air

  40. Disproving Spontaneous Generation

  41. Origin of Life • Biogenesis- living organisms only come from other living organisms

  42. Origin of Cells • Earth approximately 4.6 billion years old • Beginning- earth’s atmosphere Hot, gases like CO2 and nitrogen, little O2 • Gases helped to create the atmosphere

  43. Origin of Cells • 3.5 to 4 billion years ago • Organic Molecules  Protocells  Prokaryotic cells (heterotrophs)  First simple autotrophs/producer  Eukaryotic cells  Multicellular organisms

  44. Origin of a Species • Speciation – formation of a new species, members of similar populations no longer interbreed

  45. Origin of a Species Geographic Isolation • Physical barrier divides population • River, canyon, mtn. splits group Two species of squirrel split by the Grand Canyon

  46. Patterns in Evolution • Adaptive radiation – one ancestral species evolves into a number of species to exploit a number of habitats.

  47. Patterns in Evolution • Divergent evolution- one species evolves into two species with different characteristics (get more and more different from each other)

  48. Patterns in Evolution • Convergent evolution – distant or unrelated species evolve similar characteristics to take advantage of similar environments Example: fish and dolphin

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