Campbell Biology 11th Edition by Lisa Urry,Michael Cain,Steven Wasserman,Peter Minorsky,Jane Reece

Exercise 8

Researchers studied genetic variation in the marine mussel Mytilus edulis around Long Island, New York. They measured the frequency of a particular allele (lap94) for an enzyme involved in regulating the mussel's internal saltwater balance. The researchers presented their data as a series of pie charts linked to sampling sites within Long Island Sound, where the salinity is highly variable, and along the coast of the open ocean, where salinity is constant:
a. Create a data table for the 11 sampling sites by estimating the frequency of lap 94 from the pie charts. (Hint: Think of each pie chart as a clock face to help you estimate the proportion of the shaded area.) (b) Graph the frequencies for sites 1-8 to show how the frequency of this allele changes with increasing Evaluate how the data from sites 9 - 11 compare with the date from the sites within the sound. (c) Construct a hypothesis that for the following observations: (1) The lap 94 allele helps mussels maintain osmatic balance in water with a high salt concentration but is costly to use in less salty water; and (2) mussels produce larvae that can disperse long distances before they settle on rocks and grow into adults.