title: Maternal response to environmental unpredictability.
abstract: Mothers are expected to use environmental cues to modify maternal investment to optimize their fitness. However, when the environment varies unpredictably, cues may not be an accurate proxy of future conditions. Under such circumstances, selection favors a diversifying maternal investment strategy. While there is evidence that the environment is becoming more uncertain, the extent to which mothers are able to respond to this unpredictability is generally unknown. In this study, we test the hypothesis that Daphnia magna increase the variance in maternal investment in response to unpredictable variation in temperature consistent with global change predictions. We detected significant variability across temperature treatments in brood size, neonate size at birth, and time between broods. The estimated variability within-brood size was higher (albeit not statistically significant) in mothers reared in unpredictable temperature conditions. We also detected a cross-generational effect with the temperature history of mothers modulating the phenotypic response of F1's. Notably, our results diverged from the prediction that increased variability poses a greater risk to organisms than changes in mean temperature. Increased unpredictability in temperature had negligible effects on fitness-correlated traits. Mothers in the unpredictable treatment, survived as long, and produced as many F1's during lifetime as those produced in the most fecund treatment. Further, increased unpredictability in temperature did not affect the probability of survival of F1's. Collectively, we provide evidence that daphnia respond effectively to thermal unpredictability. But rather than increasing the variance in maternal investment, daphnia respond to uncertainty by being a jack of all temperatures, master of none. Importantly, our study highlights the essential need to examine changes in variances rather than merely on means, when investigating maternal responses.
authors.affiliation: CESAM Departamento de Biologia Universidade de Aveiro Campus de Santiago 3810 Aveiro Portugal ; Scottish Oceans Institute University of St Andrews St Andrews Fife KY16 8LB UK.
authors.forename: Miguel
authors.initials: M
authors.lastname: Barbosa
authors.affiliation: CESAM Departamento de Biologia Universidade de Aveiro Campus de Santiago 3810 Aveiro Portugal.
authors.forename: Isabel
authors.initials: I
authors.lastname: Lopes
authors.affiliation: CESAM Departamento de Biologia Universidade de Aveiro Campus de Santiago 3810 Aveiro Portugal.
authors.forename: Catia
authors.initials: C
authors.lastname: Venâncio
authors.affiliation: CESAM Departamento de Biologia Universidade de Aveiro Campus de Santiago 3810 Aveiro Portugal ; School of Biology University of St Andrews St Andrews Fife KY16 8LB UK.
authors.forename: Maria João
authors.initials: MJ
authors.lastname: Janeiro
authors.affiliation: School of Biology University of St Andrews St Andrews Fife KY16 8LB UK.
authors.forename: Michael Blair
authors.initials: MB
authors.lastname: Morrisey
authors.affiliation: CESAM Departamento de Biologia Universidade de Aveiro Campus de Santiago 3810 Aveiro Portugal ; Programa de Pós-Graduação em Produção Vegetal Universidade Federal do Tocantins Campus de Gurupi 77402-970 Gurupi Brazil.
authors.forename: Amadeu M V M
authors.initials: AM
authors.lastname: Soares
keywords: Fitness; jack of all trades; maternal Investment; trans‐generational effects; unpredictability; variance