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Sonia E. Sultan




Parental environment influences progeny development in numerous plant and animal systems. Such inherited environmental effects may alter offspring development and fitness in a consistent way, for instance when resource-deprived parents produce low quality offspring due to reduced maternal provisioning. However, because development of individual organisms is guided by both inherited and immediate environmental information, parental conditions may have different effects depending on progeny environment. Such context-dependent transgenerational plasticity has emerged as an exciting area of research, yet several key questions remain unanswered: (1) Does parental resource deprivation result in fixed effects on progeny, or can such factors lead to context-dependent effects? (2) How are these effects transmitted to offspring? (3) Do alternative parental environments lead to differences in lifetime fitness as well as juvenile phenotypes? (4) Finally, do parent-environment effects influence competitive performance?

I investigated these questions in the herbaceous annual Polygonum persicaria, a model system for plant plasticity in which adaptive transgenerational plasticity in response to parental drought stress has been documented. Light is an equally crucial resource which varies within and among natural plant habitats. Here I present the results of a series of greenhouse and growth chamber experiments testing the effects of parental shade versus sun on progeny development, fitness, and competitive success, and the transmission mechanisms. The results reveal substantial effects of parental light environment on both juvenile phenotypes and lifetime fitness that were expressed differently depending on progeny conditions. These inherited environmental effects also strongly altered plant competitive dynamics. I further show that the inhered effects of parental shade were mediated by DNA methylation state changes rather than seed provisioning.

These results contribute to an increasing body of evidence that the effects of parental environment may substantially alter progeny phenotypes, and that epigenetic mechanisms may play an important role in their transmission. Further, these effects may influence development differently depending on progeny conditions and impact both fitness variation and ecological interactions such as intraspecific competition.



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