Quantitative genetics and genotype by environment interactions for flowering time and floral morphology in Ipomopsis longiflora subsp. australis (Polemoniaceae)

Flowering phenology and floral morphology are both directly tied to overall reproductive success of flowering plants. The match between pollinator abundance and timing of flowering can greatly affect plant fitness, and flower shape and size affect attractiveness of plants to pollinators. I measured quantitative genetic parameters for flowering time (date of first flower) and floral morphology in a polycarpic desert annual, Ipomopsis longiflora subsp. australis to determine the potential for these traits to respond to selection. Significant heritabilities and coefficients of genetic variation (CVA) were found for flowering phenology and most of the floral traits measured, indicating these traits can likely respond to natural selection in natural populations. Although significant genetic correlations were calculated between many of the floral characters to assess possible constraints on floral evolution, none were detected between flowering time and floral morphology. Flowering time did have a significant genotype-by-environment interaction (GxE) in response to greenhouse and field growing conditions, indicating that there is genetic variation in plasticity for flowering time in Ipomopsis longiflora. Plasticity in flowering time may be adaptive in Ipomopsis longiflora due to temporally varying selection pressures associated with differing growing and reproductive seasons faced in the desert southwest.