Effects of paternal phenotype and environmental variability on age and size at maturity in a male dimorphic mite

Investigating how the environment affects age and size at maturity of individuals is crucial to understanding how changes in the environment affect population dynamics through the biology of a species. Paternal phenotype, maternal, and offspring environment may crucially influence these traits, but to my knowledge, their combined effects have not yet been tested. Here, I found that in bulb mites (Rhizoglyphus robini), maternal nutrition, offspring nutrition, and paternal phenotype (males are fighters, able to kill other mites, or benign scramblers) interactively affected offspring age and size at maturity. The largest effect occurred when both maternal and offspring nutrition was poor: in that case offspring from fighter sires required a significantly longer development time than offspring from scrambler sires. Investigating parental effects on the relationship between age and size at maturity revealed no paternal effects, and only for females was its shape influenced by maternal nutrition. Overall, this reaction norm was nonlinear. These non-genetic intergenerational effects may play a complex, yet unexplored role in influencing population fluctuations—possibly explaining why results from field studies often do not match theoretical predictions on maternal effects on population dynamics.