Maternal effects and parent–offspring conflict

Abstract

Maternal effects can provide offspring with reliable information about the environment they are likely to experience, but also offer scope for maternal manipulation of young when interests diverge between parents and offspring. To predict the impact of parent-offspring conflict, we model the evolution of maternal effects on local adaptation of young. We find that parent-offspring conflict strongly influences the stability of maternal effects; moreover, the nature of the disagreement between parents and young predicts how conflict is resolved: when mothers favor less extreme mixtures of phenotypes relative to offspring (i.e., when mothers stand to gain by hedging their bets), mothers win the conflict by providing offspring with limited amounts of information. When offspring favor overproduction of one and the same phenotype across all environments compared to mothers (e.g., when offspring favor a larger body size), neither side wins the conflict and signaling breaks down. Only when offspring favor less extreme mixtures relative to their mothers (something no current model predicts), offspring win the conflict and obtain full information about the environment. We conclude that a partial or complete breakdown of informative maternal effects will be the norm rather than the exception in the presence of parent-offspring conflict.

Developmental responses to early‐life adversity: Evolutionary and mechanistic perspectives

“…Despite frequent discussions of PAR and developmental constraints as contrasting models, they share remarkable similarities in their emphasis on how developmental plasticity benefits offspring, with little regard to maternal agency . However, mammalian mothers contribute substantial behavioral, chemical, and nutritional input during fetal and early postnatal life, and thus can potentially act as a filter through which information about the early environment passes …”

“…However, as parent‐offspring conflict increases, the fitness interests of mothers and offspring are expected to diverge . Under such conditions, mothers are expected to manipulate offspring development and conserve energy for future reproduction by providing inaccurate signals of the external environment, investing less, and creating “cheaper” offspring . Consequently, offspring development is unlikely to be optimally calibrated to external conditions.…”

“…Consequently, offspring development is unlikely to be optimally calibrated to external conditions. Although existing empirical data suggest that mothers are more likely to “win” this conflict, experimental studies by Kuijper and Johnstone found that maternal signals might remain at least partially informative of the current environment when alternative offspring phenotypes exact similar investment costs on the mother (as opposed to having a more expensive phenotype that benefits the offspring but is more energetically demanding on the mother). Moreover, despite presumed maternal control, neither side may reach a fitness optimum.…”

“…The resulting half‐siblings are, on average, 50% less related than full‐siblings, which may create greater selfishness on the part of offspring and a tug‐of‐war between maternal and offspring interests . Thus, clear fitness benefits for offspring might be better supported in monogamous or polygynous systems, where siblings are more closely related and less conflict exists between parent and offspring optima …”

“…49,50 However, mammalian mothers contribute substantial behavioral, chemical, and nutritional input during fetal and early postnatal life, and thus can potentially act as a filter through which information about the early environment passes. 22,51,52 The maternal capital model 23,24 developed by Wellsis the only evolutionary model that emphasizes maternal agency in shaping offspring developmental trajectories. 23,24 This model argues that developmental responses are optimally designed to increase maternal fitness, which may or may not be aligned with offspring fitness.…”