Ashvina's Education R-Evolution: Theory of Evolution by Natural Selection

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by Ashvina Isaac4 views·Updated Dec 4, 2020
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  1. theory of evolution by natural selection.
  2. Before we get too far into it, let's discuss what
  3. is a theory.
  4. Common answers would be an idea or a possibility, which
  5. is one context.
  6. The word could be used in scientific areas, the first
  7. lightly because they're tested and modified until there completely proven
  8. by multiple forms of evidence.
  9. Now that that's out of the way, the theory of
  10. evolution by natural selection, we'll break it down again to
  11. make it a bit more simple and start with the
  12. theory of evolution.
  13. The theory, more or less expresses that all organisms are
  14. related and change over time.
  15. This change over time is an effect of genetic variation
  16. caused by mutations.
  17. These mutations are the only source of new jeans in
  18. mutations can cause a slight difference to be president an
  19. organism which the parents might have, but they also might
  20. not. Let's look at an example that everyone should be
  21. somewhat familiar with the giraffe.
  22. Giraffes are a species known globally for its 2 m
  23. long legs, plus their 2 m long neck, which weighs
  24. in at about 270 kg.
  25. Ironically, today's tallest land animal urged animals original ancestor was
  26. much shorter, probably closer to a large deer.
  27. After many generations of evolving, we were left with an
  28. incredibly tall creature that has adapted to its environment to
  29. compete with those it shares its space with draft live
  30. in an area that is home to a lot of
  31. short grazers and browsers who would eat most of the
  32. food close to the ground draft started reaching up toe
  33. low tree branches.
  34. And here is where I start to mix in the
  35. theory of natural selection.
  36. After a few generations of reaching as high as they
  37. could, Draft started to produce offspring with slightly elongated necks
  38. who could comfortably reached the branches that those before them
  39. had been straining to get to.
  40. They didn't stop there, though.
  41. They just kept reaching for more and more food, which
  42. led them higher up the tree.
  43. We do not see any short drafts today because nature
  44. did not select Hm.
  45. The shortage wraps were competing with the other grazing animals
  46. and thus did not have access to his much nutritious
  47. food as the taller giraffes.
  48. Eventually, as the tall giraffes continued to procreate and produce
  49. viable offspring, the smaller and malnourished giraffes gradually died out
  50. nature favorite the longneck giraffes because they were more fit
  51. to survive.
  52. Having adapted to their environment, adaptations are necessary so that
  53. organisms may continue to evolve with the ever changing planet
  54. they live on.
  55. They inherit the advantages trait in this case, the draft
  56. longneck that will help them to survive.
  57. And the trait will be passed down through generations similarly
  58. to something like your own height or your hair color.
  59. Now that we have mentioned one way that nature may
  60. favor of species, let's talk about another.
  61. A common misconception of the phrase survival of the fittest
  62. is the meaning of the word fit.
  63. In this context, it does not have so much to
  64. do with how big and strong the organism is.
  65. It's This kind of fitness is measured by how many
  66. viable offspring it may have.
  67. Let's say that a drop that let's say that giraffe
  68. A will live a long and healthy 30 years and
  69. produce five viable offspring draft be lives on Lee 20
  70. years but produces 10 viable offspring.
  71. Draft be will be considered more fit to survive.
  72. As for natural selection, nature favors reproductive success because that
  73. ensures that the organism will not die out too quickly.
  74. And now that we have an idea of what theory
  75. of natural selection is, let's look at it a bit
  76. more closely.
  77. Charles Darwin's theory of evolution is based on five key
  78. observations, which were later dissected into three inferences.
  79. These modern, the modern theory of evolution, also happens to
  80. include more genetics.
  81. But we will just be focusing on the simplified five
  82. observations and three inferences in France.
  83. Number one individuals within a population will compete for resources
  84. under that.
  85. Under that, we find observations 12 and three one being
  86. each generation produces more offspring than adults, meaning that not
  87. all offspring are viable and will not make it to
  88. adulthood. Observation to being populations do not grow in size
  89. and three being food and other resources are limited.
  90. And then we have inference.
  91. Number two.
  92. Individuals who inherit favorable characteristics have a better chance of
  93. survival and a better chance of leaving behind multiple viable
  94. offspring compared to those who dot inherit the favorable traits.
  95. Under that, we have observation number four the characteristics of
  96. the individuals in the population.
  97. Very different versions of the same trait exist in one
  98. population in front number three.
  99. As nature favors the favorable trait, the population will change
  100. over time until it is entirely composed of organisms that
  101. inherited Detroit.
  102. Of course, there will still be some variation because of
  103. observation Number four, an observation number five that falls under
  104. inference. Three.
  105. Many variations are inheritable.
  106. Now that we have an idea of what natural selection
  107. looks like.
  108. Let's go to a more popular example where so we
  109. can apply this knowledge and make sure we understood everything
  110. correctly. You may have heard of the name Charles Darwin.
  111. I mentioned him earlier.
  112. He was a naturalist and the most important theorist when
  113. it came to natural selection.
  114. His most famous example is the finches of the Galapagos
  115. Islands. The Galapagos Islands are a group of multiple islands
  116. off the coast of Ecuador.
  117. Darwin visited the little islands and cataloged his fines.
  118. He was surprised to see that a lot of animals
  119. he saw in one island he saw again on another.
  120. But something was different when it came to the seed.
  121. Eating finch is most noticeable.
  122. Difference was their beaks on island A.
  123. The majority of the seeds that could be found where
  124. a medium size, and so most of the finches had
  125. medium sized beaks.
  126. The population continued to grow until it got to the
  127. point where supply started to run low because this large
  128. population was competing for the same source of food based
  129. on observation.
  130. Number four.
  131. We know that there has to be some sort of
  132. variety in both organisms, the finch birds as well as
  133. the seed plants.
  134. Although the average is a medium size, certain, mutated birds
  135. and plants will be very large or very small.
  136. While the medium beak sized birds fight over the medium
  137. and small seeds.
  138. The small birds will go hungry and die out because
  139. of the overpopulation of medium birds that are taking over
  140. all the medium, all of the food that they can
  141. eat. The large seeds are left almost untouched because the
  142. small and medium sized birds are not capable of eating
  143. them. The few finches that have mutations that caused them
  144. toe have ah, large beak will be well nourished and
  145. will be healthy enough to produce more viable offspring than
  146. the two smaller sizes.
  147. Even though Island A was favorable towards the large beaked
  148. finches island, be may be favorable for those favorable to
  149. the small finches for other reasons, it really depends on
  150. who the environment select as best fit.
  151. Thank you for listening to what I had to say,
  152. and I hope this gave you a small amount of
  153. understanding of the great theory of natural selection.
  154. And maybe this can even be your inspiration to take
  155. a deeper dive into the topic.