lesson 5 -adaptations

• What is the definition of adaptations in the context of evolution?


  Changes in the genetic makeup of a population over time
• Why isn't the time frame of evolution defined?


  Because evolution occurs over varying lengths of time
• In which century did scientists begin to believe that animals changed over time?


  The 1800s
• What types of evidence supported the idea that animals change over time?

  Fossils, embryology, biogeography, comparative anatomy, and selective breeding
• What modern tools were not available to scientists in the 1800s?


  Molecular tools like DNA sequencing
• How has DNA sequencing impacted our understanding of evolution?


  It has confirmed certain relationships and helped rearrange branches on the tree of life
• What is natural selection?


  Over time, animals become better adapted to their environments
• What is an adaptation?


  Any trait that allows an organism to better survive or reproduce in its environment
• What must organisms possess for natural selection to occur?


  They must be born with the genes for adaptation
• What happens when an organism survives and reproduces in the context of natural selection?


  The "good" gene becomes more prevalent in the population over generations
• What is the "jumping board" to evolution according to natural selection?


  Variation within a population
• What are two sources of variation within a population?

  Sexual reproduction and random DNA mutations
• How does variation within a population affect its survival?


  The more variation, the more likely the population can survive/adapt to changes
• What is an example of evolution that is observable in nature?


  The adaptation of peppered moths
• What does genetic drift refer to?


  Changes in populations due to chance random events that reduce genetic variation
• What is the bottleneck effect?


  A significant contraction of a population into a smaller size by a sudden event
• What is the founder effect?


  A small group in a population splinters off from the original population
• What is the evolutionary sequence of life on Earth as mentioned in the study material?


  Fish → Amphibians → Reptiles → Mammals
• What event killed off most of the dinosaurs 65 million years ago?


  An asteroid impact
• What happened to the shrew-like creature after the dinosaurs went extinct?


  It filled many unused niches and underwent massive speciation
• What is the significance of the shrew-like creature in relation to mammals today?


  It is the descendant of all mammals today