Document: HIL-3-46-16

Complex plasticity in complex environments: Early spring flowering in Arabidopsis thaliana.

CALLAHAN, H.* ¹, N.KURASHIGE ¹, C.ANCELL ² and M.PIGLIUCCI ²

Barnard College, Columbia University, New York, NY 10027 USA ¹
University of Tennessee, Knoxville TN 37996 USA ²

Abstract:
Multiple environmental factors accelerate or delay flowering time, affecting both individual fitness and population growth. Some factors are predictable (photoperiod), others more variable (temperature). Large-scale phenomena (long-distance migration, climate change) may disrupt the predictability of any given factor. We investigated the extent to which complex environmental variation and complex plasticity are related in Arabidopsis thaliana. In this model species, flowering time responds plastically to at least three seasonally-variable, light-related factors: intensity, spectral quality, and photoperiod. It also responds to a fourth seasonally-variable factor, vernalization. Arabidopsis typically flowers during the transition from winter to spring, when all four factors may change in an imperfectly concordant fashion. Unlike molecular geneticists, who study how multiple photoreceptors and light- or vernalization-sensitive loci are integrated in Arabidopsis, we examine flowering time plasticity from an evolutionary ecology perspective. We report results of an artificial selection study conducted with a wild, naturally variable, spring-flowering population from Michigan. We selected two "high" and two "low" lines for enhanced or diminished plasticity to light with a reduced red to far-red ratio. Although only the two high lines diverged significantly from two random control lines, we were able to use among-family variation in all six lines to examine genetic correlations among traits and trait plasticities. We found that correlations between flowering time and total fruit production are extremely environment-dependent. We also found non-significant correlations between light- and vernalization-mediated plasticities of flowering time. Results are consistent with models based on molecular genetic data. Moreover, the strengths of such correlations may impose constraints on the adaptive evolution of flowering time and its phenotypic plasticity.

Keywords: genotype-by-environment interaction, indirect selection, phenology, phenotypic plasticity, reaction norm

This abstract is being presented at: 2:30 PM in session:
Oral Session #63: Evolutionary Ecology.