Refer to Practice Problem 16.

a. Plot the null probability distribution for this case.

b. What is the meaning of this distribution?

Data from problem 16

In 1964, Ehrlich and Raven proposed that plant chemical defenses against attack by herbivores would spur plant diversification. In a test of this idea (Farrell et al. 1991), the number of species in 16 pairs of sister clades whose species differed in their level of chemical protection were counted. In each pair of sister clades, the plants of one clade were defended by a gooey latex or resin that was exuded when the leaf was damaged, whereas the plants of the other clade lacked this defense. In 13 of the 16 pairs, the clade with latex/resin was found to be the more diverse (had more species), whereas in the other 3 pairs the sister clade lacking latex/resin was found to be the more diverse.