Ecology 5th Edition by Manuel Molles

Exercise 14

Would you expect the number of species to remain indefinitely at the level shown in figure 20.7? Space on large stable boulders in Sousa's study site is dominated by the algal G.canaliculata and support 2.3 to 3.5 species, not the 5 shown in figure 20.7. Explain. (Hint: How long did Sousa follow his study boulders?)
Figure 20.7 Succession in number of macroinvertebrate and macroalgae species on intertidal boulders (data from Sousa 1979a).