Data used in: The causes and consequences of seed size variation in the California-native annual species, Nemophila menziesii

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 Seed size is a critical factor in determining various aspects of a plant’s life cycle, such as germination rate, seedling size, and survival. The sources of variation in the trait are essential to understand its adaptive potential to changing environments. This study evaluates the genetic and environmental influences on seed size variation within and among four wild populations of Nemophila menziesii, a widespread California annual herb. By leveraging a greenhouse breeding experiment with a nested half-sibling mating design, this study examines the magnitude of additive genetic variance and heritability of seed size within populations, the concordance between different heritability estimation methods, and the contribution of the maternal and paternal parents to seed size. Mean seed size differed significantly among populations, regardless of growing location, while the magnitude of plasticity in response to environmental conditions was similar among populations. The study revealed a..., ,