Marine crustaceans show a suite of phenotypically plastic responses to the environment, with some restricted to the larval phase and others transcending life history boundaries, linking life phases or generations. Maternal effects include the effects of allocation of reserves into eggs as well as effects of the embryonic environment on tolerance to low salinity or larval body mass. Within the larval phase, there is a diversity of plastic responses involving changes in body size, growth, and developmental rate; they can occur within the molt cycle, involve several molting stages, or result in the development of alternative pathways characterized by the different larval stages. In feeding larvae, the effects of stressors on body mass may be attenuated by delayed development; however, in nonfeeding larvae (e.g., barnacle cyprids), delayed metamorphosis reduces juvenile body size and habitat selectivity. Also, larval food limitation and increased temperatures away from the optimum lead to reduced body mass during metamorphosis. Overall, many of these responses are adaptive and lead to the maintenance of basic functions at the expense of morphogenesis and growth. Some plastic responses that lead to changes in size during metamorphosis can also have consequences for juvenile size growth and survival. These “latent effects” appear to represent forms of developmental trade-offs and may have important ecological and evolutionary consequences. Larval plasticity, by generating phenotypic variation, may influence the capacity to compete, capture resources, tolerate stressors, and, ultimately, may affect recruitment dynamics. In addition, plastic responses linking life history stages also result in genetic links and hence drive the evolution of crustaceans with complex life cycles.
Body Mass Increase Induced by Eight Years of Artificial Selection in the Yellow Mealworm (Coleoptera: Tenebrionidae) and Life History Trade-offs
