In sand dollar (Dendraster excentricus) larvae, the plasticity of feeding arm growth in response to food ration depends on the density of potential competitors. Photo: Jason Hodin

Kacenas SE, Podolsky RD


Density-dependent expression of plasticity in larval morphology: effects of actual and apparent competitors

Larvae of marine invertebrates are cultured for laboratory studies at densities substantially higher than typical in the field. Growth of larger feeding structures under more limiting food conditions has been demonstrated in several taxa. Along with a similar larval plastic response to high larval density (greater potential for competition), Kacenas & Podolsky found a loss of the plastic response to food ration when reared closer to field densities. These results did not depend on whether potential competitors were conspecific, heterospecific, or only apparent (non-feeding), suggesting that larvae responded directly to competitor presence rather than indirectly to a food decline. These density-dependent effects have broad implications for inferences from studies of cultured larvae and from the morphology of field-collected larvae.


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