Data from: Maternal effects and maternal selection arising from variation in allocation of free amino acid to eggs

Maternal provisioning can have profound effects on offspring phenotypes,
or maternal effects, especially early in life. One ubiquitous form of
provisioning is in the makeup of egg. However, only a few studies examine
the role of specific egg constituents in maternal effects, especially as
they relate to maternal selection (a standardized selection gradient
reflecting the covariance between maternal traits and offspring fitness).
Here, we report on the evolutionary consequences of differences in
maternal acquisition and allocation of amino acids to eggs. We manipulated
acquisition by varying maternal diet (milkweed or sunflower) in the large
milkweed bug, Oncopeltus fasciatus. Variation in allocation was detected
by examining two source populations with different evolutionary histories
and life-history response to sunflower as food. We measured amino acids
composition in eggs in this 2 × 2 design and found significant effects of
source population and maternal diet on egg and nymph mass and of source
population, maternal diet, and their interaction on amino acid composition
of eggs. We measured significant linear and quadratic maternal selection
on offspring mass associated with variation in amino acid allocation.
Visualizing the performance surface along the major axes of nonlinear
selection and plotting the mean amino acid profile of eggs from each
treatment onto the surface revealed a saddle-shaped fitness surface. While
maternal selection appears to have influenced how females allocate amino
acids, this maternal effect did not evolve equally in the two populations.
Furthermore, none of the population means coincided with peak performance.
Thus, we found that the composition of free amino acids in eggs was due to
variation in both acquisition and allocation, which had significant
fitness effects and created selection. However, although there can be an
evolutionary response to novel food resources, females may be constrained
from reaching phenotypic optima with regard to allocation of free amino
acids.