The price of defence: Maternal effects in an aposematic ladybird

Abstract

Offspring phenotype can be adaptively altered via maternal non-genetic inheritance. Such ‘maternal effects’ enable females to adjust their per offspring investment in response to variation in the offspring environment, and thus maximise their reproductive success. Consequently they play a pivotal role in population dynamics and the response of species to environmental change. Despite this, little is known about how maternal effects mediate reproductive investment in response to multiple or novel environmental changes, such as those driven by anthropogenic activity. I use the 2-spot ladybird intraguild predation system, where resources and predation risk are highly variable, to explore the role of maternal effects in the response of a native species to an invasive predator, as well as answering outstanding questions about how maternal effects function under complex and antagonistic sets of variables. The results indicate that it is unlikely that maternally mediated changes in egg phenotype will improve the survival of 2-spot ladybird offspring in the face of predation from larvae of the invasive harlequin ladybird. They do, however, demonstrate the importance of studying maternal effects in the context of the multiple environmental factors, which more accurately represent the complex environments in which organisms live and evolve, corroborating recent theoretical predictions. Finally I provide evidence of the multifaceted nature of parental effects in aposematic species and reveal the role that they may play in shaping the variation in defence and warning coloration observed in adult populations.