Chap 15 Darwin and Evolution Study Guide


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Biology Darwin and Evolution Study Guide


15.1: The puzzle of life’s diversity

Understand these words:

  • Evolution – Change over time; the process by which modern organisms have descended from ancient organisms
  • Theory (scientific) – A well-supported tested explanation of phenomena that has occurred in the natural world
  • Fossil – preserved remains of ancient organisms

What is biological diversity? The variety and abundance of species that make up a biological community.

Darwin’s Life and travels - video questions

1.Why did Darwin’s ideas clash with Victorian Culture?

  • The Bible said in "Genesis" believe that god created each species and these species stay fixed
  • Went across all of natural history
  • Would break established link of science, politics, and the church
    • God selected the kings and queens to be in power
      • If this idea is broken it could cause (gasp) democracy
      • People were like animals

2. What is the "mystery of mysteries"?

  • The original appearance of species.

3. What habits made Darwin especially suited to be a scientist?

  • Hardwork
  • 23 years of work
  • Observative skills
  • Interest in science

4. Did Darwin work completely alone, "in a vacuum"?

  • Worked pretty much alone, except with his brother
  • No, he read the work of other famous scientists of Malthus and is shown in the video talking to other scientists

5. What were some of Darwin’s observations?

  • An ancient common ancestor
  • Similar traits
  • Same environment does not equal same species
  • Animals are all fit to their habitat

6. Why were the islands a great place to make these observations?

  • They were close together, but had different climates.

Darwin’s observations: how did these contribute to Darwin’s theory? 1. Patterns of Diversity – Plants and animals well suited for environment which they live in. But similar environments on different continents did not equal the same species. 2. Living organisms and fossils – Some fossils looked very similar to living species but some looked like nothing else which was alive 3. The Galapagos Islands – 1000km west of South America – Very different climates on each island – Some low, hot, and dry – others had more rainfall and a richer vegetation

15.2 Ideas that shaped Darwin’s thinking

Describe the contributions of the following scientists to Darwin’s thinking:

  • Hutton and Lyell – Earth changes slowly over millions of years (rocks, rivers, erosion) – World is older than a few thousand years old (which was current thought) – Science must explain past events in the context of observable events – Could life change over time like the earth had?
  • Malthus – economist who said that the Earth’s population was growing too fast for the scarce resources on Earth – War, starvation and disease would lessen the problem – Darwin thought the same thing went for organisms
  • Lamarck – theory of evolution by acquired traits (giraffe – kept stretching its neck to get food, so that its offspring would be born taller) [By this logic humans could develop offspring which could fly; or that a baby born to cyclers would have good legs] WRONG
    • 1. Tendency towards perfection
    • 2. Use and Disuse
    • 3. Inheritance of Acquired Traits

15.3 Darwin’s case: how did the following contribute to what he proposed?

  • Natural variation –Variations occur due to random mutations in genes
  • Artificial Selection – breeding animals which have the traits you wanted – continue to breed the plants and animals of traits you want (Broccoli was breed from wild mustard)

Evolution by Natural Selection: what do each of the following mean?

  • The Struggle for Existence – Members of each species compete regularly to obtain food, living space, and other necessities of life
  • Survival of the Fittest – Organisms who are best adapted for the environment will survive to produce many offspring
  • fitness - The ability of organisms to survive and reproduce in its environment
  • adaptation (physical or behavioral) – Any inherited characteristics that increase an organism’s chance of survival
  • natural selection - Life is ruled by a struggle for existence where the strongest or organisms best suited for the environment survive and reproduce – weak organisms or those without the best traits die off, producing little to no offspring – thus the offspring that are left are the strongest (Variations occur due to random mutations)
  • Descent with Modification – Over long periods of time, natural selection produces organisms that have different structures, establish different niches, or occupy different habitats so that organism look different than their distant organisms
  • common descent – Over an extremely long period of time, there is a common ancestor for all living things

Evidence of Evolution

  1. The Fossil Record – From studying the different fossils contained in different levels of rock, we can see that life on Earth has changed over time and is older than a few thousand years
  2. Geographic Distribution of Living Species – Although organisms were separated, they evolved to be different but share similar structures. Also the fact that different organisms live on different continents even though the climate is the same.
  3. Homologous Body Structure – The body parts of animals with backbones are very similar. The limbs of reptiles, birds, and mammals (arms, wings, legs, and flippers) are very similar. Some vestigial organs are still there even though they have no use since they provide no advantage or disadvantage for the organism.
  4. Similarities in Embryology – The early embryo stages in animals with backbones are very similar.

Summary of Darwin’s Theory: What are the 8 points? p386

  1. Individual organisms differ, and some of this variation is heritable
  2. Organisms produce more offspring than can survive, and many that do survive do not reproduce
  3. Because more organisms are produced than can survive, they compete for limited resources
  4. Each unique organism has different advantages and disadvantages in the struggle for existence. Individual best suited to their environment survive and reproduce most successfully. These organisms pass their heritable traits to their offspring. Other individuals die or leave fewer offspring. The process of natural selection causes species to change over time.
  5. Species alive today are descended with modification from ancestral species that lived in the distant past. The process by which diverse species evolved from common ancestors, unites all organisms on Earth in a single tree of life.