Abstract
Maternal effects are prevalent in nature and significantly contribute to variation in phenotypic trait expression. However, little attention has been paid to the factors shaping variation in the traits mediating these effects (maternal effectors). Specific maternal effectors are often not identified, and typically they are assumed to be inherited in an additive genetic and autosomal manner. Given that these effectors can cause long‐lasting effects on offspring phenotype, it is likely that they may also affect themselves in the next generation. Although the existence of such cascading maternal effects has been discussed and modeled, empirical examples of such effects are rare, let alone quantitative estimates of their strength and evolutionary consequences. Here, we demonstrate that the investment a mother makes in her eggs positively affects the egg investment of her daughters. Through reciprocally crossing artificially selected lines for divergent prenatal maternal investment in Japanese quail (Coturnix japonica), we demonstrate that the size of eggs daughters lay resembles the egg size of their maternal line significantly more than that of their paternal line, highlighting that egg size is in part maternally inherited. Correspondingly, we find that variation in the daughters' egg size is in part determined by maternal identity, in addition to substantial additive genetic effects. Furthermore, this maternal variance in offspring egg size is fully explained by maternal egg size, demonstrating the presence of a positive cascading effect of maternal egg size on offspring egg size. Finally, we use an evolutionary model to quantify the consequences of covariance between cascading maternal and additive genetic effects for both maternal effector and offspring body mass evolution. Our study demonstrates that by amplifying the amount of variation available for selection to act on, positive cascading maternal effects can significantly enhance the evolutionary potential of maternal effectors and the offspring traits that they affect.
Highlights
The more you get, the more you give: Positive cascading effects shape the evolutionary potential of prenatal maternal investment
Through reciprocally crossing artificially selected lines for divergent prenatal maternal investment in Japanese quail (Coturnix japonica), we demonstrate that the size of eggs daughters lay resembles the egg size of their maternal line significantly more than that of their paternal line, highlighting that egg size is in part maternally inherited
We further demonstrate that this association between additive genetic and positive cascading maternal effects leads to an amplification effect, accelerating the evolutionary potential of both maternal investment and any other traits in offspring affected by this maternal investment
Summary
The more you get, the more you give: Positive cascading effects shape the evolutionary potential of prenatal maternal investment. Specific maternal effectors are often not identified, and typically they are assumed to be inherited in an additive genetic and autosomal manner Given that these effectors can cause long-lasting effects on offspring phenotype, it is likely that they may affect themselves in the generation. Our study demonstrates that by amplifying the amount of variation available for selection to act on, positive cascading maternal effects can significantly enhance the evolutionary potential of maternal effectors and the offspring traits that they affect. As well as passing on genes, a mother shapes her offsprings phenotype by influencing the environment they experience early in life Such maternal effects are ubiquitous in nature and are recognized for their impact on phenotypic trait expression.
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