Morphological plasticity and apparent loss of apical dominance following the natural loss of the main apex in Pterocladiella capillacea (Rhodophyta, Gelidiales) fronds

In an intertidal population of Pterocladiella capillacea from southern Baja California, Mexico, fronds that lacked their main apex were bushier than intact fronds. A multivariate statistical analysis showed that the absence of the main apex was associated with higher frond biomass, a higher degree of branching, higher frond width, and longer main branches. The variation in frond form when the main apex is absent might be a response to the loss of apical dominance. The potential relevance of this morphological plasticity for the survival of thalli in the intertidal zone is discussed.