When to rely on maternal effects and when on phenotypic plasticity?

Area of Science:

• Evolutionary biology
• Quantitative genetics
• Ecology

Background:

• Maternal effects are known to impact evolution, but their own evolutionary dynamics are poorly understood.
• Previous models assumed maternal effects are constant, neglecting their adaptive potential.
• Understanding how natural selection shapes maternal effects across diverse ecological settings is crucial.

Purpose of the Study:

• To develop an evolutionary model of maternal effects within a quantitative genetics framework.
• To investigate how maternal effects evolve under different environmental conditions (constant, abrupt change, fluctuating).
• To determine the influence of selection strength and plasticity on maternal effect evolution.

Main Methods:

• Derivation of an evolutionary model for maternal effects.
• Analysis of maternal effect evolution in constant, abruptly changing, and periodically fluctuating environments.
• Examination of the interplay between selection, plasticity, and maternal effects.

Main Results:

• In constant environments, maternal effects evolve towards negative values, reducing phenotypic variance (canalization).
• In changing environments, maternal effects transiently evolve to positive values, aiding adaptation.
• Fluctuating environments show maternal effects evolving based on environmental autocorrelation, favoring positive effects with slow change and negative with rapid change.
• Strong selection and constrained plasticity lead to the strongest maternal effects.
• Weak selection allows phenotypic plasticity to broaden the scope of maternal effects, but their magnitude is reduced.

Conclusions:

• Maternal effects are not evolutionarily constant and adapt to environmental conditions.
• The direction and magnitude of maternal effects are shaped by selection, environmental stability, and plasticity.
• Identifying significant maternal influences on offspring may be challenging in weakly selected traits due to plasticity.