| Summary: | Maintaining global food security in the presence of a growing food demand and climate change will require an improved understanding of the genetic basis of crop yield components, and their response to environmental stress conditions, such as drought. The reproductive output of plants is further limited by partitioning of finite resources, resulting in trade-offs between traits. Here, I address these issues using Multiparent Advanced Generation Inter-Cross (MAGIC) lines of Arabidopsis thaliana for quantitative trait locus (QTL) analysis, and find that (i) there is no evidence for a genetic basis of the seed size/number trade-off, and (ii) A. thaliana responds to drought predominantly via phenotypic plasticity. I also show that seed size affects the probability of seeds germinating in the field. Moreover, I demonstrate that the inflorescence contributes resources to fitness, which suggests that flowering time and vegetative size do not necessarily impose an upper limit on reproductive output. Lastly, I address the evolution of genomic imprinting, as several imprinted genes have been shown to be vital for seed development. Several hypotheses for the evolution of genomic imprinting are tested simultaneously, and I find evidence to support a link between transposable elements and imprinted genes.
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