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Mak Monaco Laboratory 3 Write-Up: Introduction to Evolution II Due to the length of this lab, there are no post lab questions. Each question is worth 0.5 points. II. Stickleback Evolution Virtual Lab 1. Define “model organism.” A “model organism” is a non-human species that is studied extensively to understand biological phenomena. 2. Why is the threespine stickleback a model organism for studies in evolution? (List at least two reasons.) The three-spine stickleback fish are small and have shorter generations. This makes them easier to keep in a lab and makes them useful for genetic studies. 3. How do spines protect ocean stickleback fish? The spines protect stickleback fish by simultaneously flaring out from the pelvic ad dorsal spines. This makes it a lot harder for predators to swallow them. 4. Describe where its spines are located. The stickleback fish has three spines on its dorsal side and two spines projecting from the pelvis on the ventral(front) side. 5. The loss of stickleback pelvic spines is similar to the loss of which body parts in some other four- legged vertebrates? It is similar to the loss of hind limbs. 6. Name two other vertebrate animals whose evolutionary histories included the loss of hind limbs. Snakes and whales evolutionary histories included the loss of hind limbs. 7. In addition to the spines, what is another component of the “armor” of a stickleback fish? Another component of armor for the stickleback fish are the row of plates on each side of the body. 8. Explain how the stickleback armor protects the fish from some predators. The back spines and pelvic spines stick out making it har for predators to swallow. The plates also make the stickleback fish hard to eat. Why are reduced pelvic phenotypes not observed in saltwater marine sea populations?Why? The reduced pelvic phenotypes have never been observed in marine and sea-run populations; the pelvic spines protect marine and sea-run sticklebacks from larger fish that prey on them in the ocean.
Which of the following best describes the likely results of the scientists investigation of the fitness of the sticklebacks that were originally from a marine environment?The fitness of the sticklebacks from the marine environment decreased because their chance of survival and reproduction is greater in the freshwater environment than in the environment.
Which of the following is an explanation for why the stickleback is a model organism for studying evolution?Which of the following is an explanation for why the stickleback is a model organism for studying evolution? Stickleback populations have evolved recently and repeatedly in postglacial lakes. Researchers have identified some of the genetic mechanisms involved in the evolution of stickleback populations.
What do you think might be an explanation for why Morvoro lake contains fish with and without pelvic spines?27. What do you think might be an explanation for why Morvoro Lake contains fish with and without pelvic spines? Answers will vary. It is possible that the population in Lake Morvoro is in the process of changing from a population of fish with mainly pelvic spines to one without pelvic spines, or vice versa.
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Which one of the three pelvic girdle phenotypes is analyzed in more detail in this experiment?
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