Meeting Abstract
Phenotypic plasticity occurs when an organism changes its phenotype in response to its environment with no concomitant change in genotype. A lag time between sensing the environment and phenotype production can occur when the environment is finely grained, i.e. when the environment changes faster than the organism can respond. Previous research has shown that marine invertebrate larvae can respond to changes in external food concentrations by altering the lengths of their feeding structures. Although most lab experiments of this phenomenon in echinoid larvae routinely only examine responses to absolute differences in the mean concentrations of food, previous research has demonstrated that organisms can cue on both the range (maximum and minimum) of food concentrations as well as the mean. What remains unknown, however, is how the timing of exposure to maximum or minimum food concentrations affects the expression of larval feeding structure plasticity. We reared larvae of Lytechinus variegatus under equal food means, but varying food maximums and minimums across a 12-day developmental period. By manipulating the point of development in which larvae receive the food maximum or minimum, we can understand how the timing of exposure to food and further, the environmental grain, are associated with feeding structure plasticity. Our preliminary observations suggest that larvae reared in coarse-grained environments (low or high) produce arms that correspond to the primary food level (long arms in low and short arms in high), whereas larvae reared in a fine-grained, fluctuating food environment produce arms that are intermediate in length. These results suggest that a lag time in the production of feeding structures may be associated with exposure to a fine-grained environment in this system.
