Role of accelerated developmental pathway and limited nurturing capacity on soldier developmental instability in subterranean termite incipient colonies
In the subterranean termite Coptotermes gestroi (Wasmann), soldiers developing in incipient colonies display strong fluctuating asymmetry when compared with soldiers developing in mature colonies. This strong asymmetry may arise from two different types of stress factors on individuals. First, the accelerated development of nanitic (small) soldiers may impose a direct physiological stress as Coptotermes soldiers produced in incipient colonies have two less molting events than soldiers produced in mature colonies. Second, the environmental conditions in incipient colonies present a major constraint with limited access to resources and small numbers of workers to care for the developing brood. In this study, 459 soldiers from 73 incipient colonies (6-month-old) displaying only nanitic soldiers were investigated in a range of nurturing capacity scenarios. Nanitic soldiers developing in incipient colonies with high nurturing capacity displayed more symmetrical traits than the ones developing in colonies with low nurturing capacity. In addition, the first soldiers to emerge in the colony were the most asymmetrical individuals, showing that as the conditions improve rapidly with the growth of the colony, newly produced nanitic soldiers manifest the lessening of stress in normalization of their morphology. However, the nurturing capacity of the colony only partially explained the developmental instability variability, implying that the accelerated development of nanitic soldiers remains an important stress factor in incipient colonies, in comparison with soldiers developing in mature colonies with two additional molts and homeostatic environmental conditions.