Date of Award
Robin M. Tingthitella, Ph.D.
Epigenetics, Gene expression, Mate choice, Maternal effect, Parental effect, Paternal effect, Stress hormones
Parental experience can alter the developmental and rearing environments of offspring, resulting in parental effects on offspring traits. I addressed the consequences of stress-induced maternal, paternal, and joint parental effects from both ultimate (ecological/evolutionary) and proximate (physiological/epigenetic) perspectives. I used a full-factorial design in which threespine stickleback (Gasterosteus aculeatus) mothers, fathers, both, or neither were exposed to a model predator at developmentally appropriate times to test for predator-induced maternal, paternal, and joint parental effects on daughters’ mating behavior and egg glucocorticoids (stress hormones) and on offspring gene expression. Maternal and paternal predator exposure independently yielded daughters who preferred less conspicuous mates with duller nuptial coloration and who courted less vigorously, relaxing (paternal) or reversing (maternal) typical preference for conspicuous males. The combined effects of maternal and paternal predator exposure were not cumulative; when both parents were predator-exposed, single-parent effects on daughters’ mate preferences were reversed. Therefore, parental effects may alter the direction of sexual selection. I tested the concentration of glucocorticoids, specifically cortisol, in the eggs of daughters post-mating trial using an enzyme-linked immunosorbent assay (ELISA). Daughters of predator-exposed parents (both parents exposed to model predator) had higher glucocorticoid concentrations in their eggs than daughters of control, unexposed parents. Daughters of predator-exposed mothers-only and predator-exposed fathers-only did not differ from control or jointly predator-exposed parents’ daughters. Therefore, predator-induced parental effects impact the gametes of their daughters, suggesting a mechanism through which predation risk may indirectly influence the next generation (grand-offspring). Finally, offspring gene expression varied with the source of parental effects: maternal and paternal effects on offspring gene expression were similar to each other, but each was different from joint parental effects. There were no differences in offspring gene expression when parent and offspring matched and mismatched (when offspring did or not experience direct predation risk themselves), perhaps because of the animals’ age at direct exposure and the specific method of predator-exposure used in this study. Maternal and paternal effects appear to be underlain by different epigenetic changes that yield independent, but perhaps additive, variation to offspring gene expression that could have an array of impacts on offspring phenotypes. Thus, stress-induced maternal, paternal, and joint parental effects may potentiate rapid transgenerational responses to novel and changing environments.
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Lehto, Whitley Rayen, "Proximate and Ultimate Consequences of Stressed-Induced Maternal, Paternal, and Joint Parental Effects in a Changing World" (2019). Electronic Theses and Dissertations. 1595.
Received from ProQuest
Whitley Rayen Lehto
Evolution & development, Ecology