Community-wide character displacement in barnacles: a new perspective for past observations

We tested for community‐wide character displacement of feeding leg length and shell morphology in two barnacle communities on the west coast of North America (southern California, USA and Vancouver Island, Canada). Neither community exhibited even displacement in shell morphology. Both barnacle communities, however, exhibited remarkably evenly displaced feeding leg length, despite large differences in geography and species composition (between the orders Pedunculata and Sessilia). Previous experiments suggest that this pattern results from competition, although the competitive mechanism remains unknown. Displacement of leg length may reflect dietary specialization, spatial competition, or both. In some cases the results from two null models differed, illustrating the importance of employing a null model that considers mean and variance, rather than character means alone. Overall, the observed pattern of character displacement provides a new perspective for re‐examining the complex relationship between morphology and interspecific competition among intertidal barnacles.