Scarlet king snakes (left photo) are relatively harmless snakes from the southeastern United States. Most individuals have a conspicuous color pattern very similar to the extremely venomous coral snake (right photo). The king snake mimics are thought to gain a survival advantage when coral snakes are present, because predators have learned to avoid coral snakes. However, king snakes also live well outside the range of coral snakes, where the conspicuous colors of these mimics should make them more vulnerable than non-mimic king snakes, because the predators have not learned to avoid coral snakes. To test this, Harper and Pfennig (2008) compared predation rates on mimic and non-mimic king snake color patterns at locations with varying distance from the boundary of the range of coral snakes. The results are given in the table. The first variable is the distance in km between each study location and the boundary of the area where coral snakes are present. Negative numbers mean locations inside the range of coral snakes, and positive numbers mean locations outside the range. At each location, plasticine dummies of king snakes were set out in the habitat, with half the dummies painted to look like mimics and the other half like less-conspicuous non mimics. The second variable in the table is the proportion of attacks by predators on the mimics at each location.

a. Give the equation for the line that best predicts proportion of attacks on mimics from the distance to the boundary. What is the trend? Assume that the relationship is linear over the range of the data (being a proportion, the true relationship cannot extend below zero or above one).

b. Test the hypothesis that distance to the boundary predicts the proportion of attacks on mimics.

Transcribed Image Text:

Distance from boundary -97-97 -47-47 -33-33 -23-23 -72-72 -23-23 152152 -15-15 9797 113113 105105 8080 138138 148148 152152 4949 4848 Proportion of attacks on mimics 00 0.010.01 00 00 0.330.33 0.50.5 0.40.4 0.670.67 0.660.66 0.660.66 11 11 11 11 11 0.40.4 00