BIOL1020_Lab4

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Biology

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Dec 6, 2023

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BIOL1020 Online Lab 4 Part B: Darwinian Snails Blackboard Assignment This assignment is in addition to completing the lab within SimBio, where you are required to complete the Feedback Questions AND the Graded Questions by the deadline. In the SimBio Darwinian Snails experiment you conducted a simulation based on a classic experiment by Robin Hadlock Seeley in 1986. Read the research paper (.pdf available in Blackboard) and answer the following questions in your own words. Save the file as a new document, name it “LastName_FirstName_CourseID_Lab#.docx” (e.g. Smith_Jane_BIOL1020_Lab4.docx), and upload it to the Dropbox by the deadline. 1. What is the observation that Seeley noted that led to the research? (1 mark) ANS. – Seeley observed that shell thickness and shell shape of the snail Littorina obtusata changed markedly between 1871 and 1984 in northern New England. 2. What is the causal (open-ended) question that Seeley was seeking to answer? (2 marks) Hint: You are unlikely to find this specifically stated in the research paper, but you should be able to formulate the causal question based on what you learned in the SimBio lab and based on reading the paper. Remember to phrase it in terms of “Why” or “What causes…etc.”. Causal questions do not start with “Does” or “How” (which are closed ended questions). ANS. – “What causes the changes in the shell thickness and shell shape of the intertidal snails Littorina obtusata ?” is the causal question that Seeley was seeking to answer. 3. What is the hypothesis that Seeley was testing? (2 marks) Hint: This can be determined from the Abstract, but don’t expect a research paper to necessarily state explicitly “We tested the hypothesis that….”). ANS. – Seeley hypothesized that the rapid morphological transition seen in the intertidal snail Littorina obtusata between 1871 and 1984 was a response to intense directional selection by the crab Carcinus maenus. 4. Seeley talks in the Introduction about “punctuated equilibrium”. What is “punctuated equilibrium” and who is credited with originally presenting this idea? (3 marks) ANS. – The idea of “punctuated equilibrium” refers to evolutionary changes occurring in plants and animals primarily through short bursts of intense speciation which are followed by prolonged periods of stasis (i.e., a state of inactivity or equilibrium). Stephen Jay Gould and Niles Eldredge are credited with originally presenting the idea of “punctuated equilibrium”.
5. What does Seeley conclude about the results of the experiment with respect to “punctuated equilibrium”? In other words, what does Seeley conclude about abrupt morphological transitions in the fossil record? (2 marks) ANS. – After conducting the field/lab experiments and genetic analyses, Seeley concluded that abrupt morphological transitions appearing in the fossil record may be a product of Darwinian selection and that the rapid morphological evolution caused in these populations due to Darwinian processes of selection result in a pattern like that of the punctuated equilibrium model. Seeley also concluded that these changes should not be assumed to represent speciation.
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