Inflorescence characteristics as function‐valued traits: Analysis of heritability and selection on architectural effects

Abstract

Production of multiple flowers in inflorescences allows the reproductive phenotypes of individual plants to include systematic among-flower variation, which could be adaptive. Systematic trait variation within inflorescences could arise from resource competition among flowers, or be a developmentally determined feature of flower position, regardless of resource dynamics. The latter, architectural effect typically manifests as continuous floral variation within inflorescences. For architectural effects to be adaptive, floral trait variation among individuals must covary with reproductive performance and be heritable. However, heritability and phenotypic selection on gradients of variation cannot be estimated readily with traditional statistical approaches. Instead, we advocate and illustrate the application of two functional data analysis techniques with observations of Delphinium glaucum (Ranunculaceae). To demonstrate the parameters-as-data approach we quantify heritability of variation in anthesis rate, as represented by the regression coefficient relating daily anthesis rate to inflorescence age. SNP-based estimates detected significant heritability (h 2 ¼ 0.245) for declining anthesis rate within inflorescences. Functional regression was used to assess phenotypic selection on anthesis rate and a floral trait (lower sepal length). The approach used spline curves that characterize within-inflorescence variation as functional predictors of a plant's fruit set. Selection on anthesis rate varied with inflorescence age and the duration of an individual's anthesis period. Lower sepal length experienced positive selection for basal and distal flowers, but negative selection for central flowers. These results illustrate the utility and power of functional-data analyses for studying architectural effects and specifically demonstrate that these effects are subject to natural selection and hence adaptive.

Integrating transcriptomic network reconstruction and QTL analyses reveals mechanistic connections between genomic architecture andBrassica rapadevelopment

“…Plant developmental genetics are correlated with fitness and yield (Baker et al 2015; 80 Kulbaba et al 2017). Therefore, characterizing the mechanistic connections between the 81 genetic architecture governing plant development and the resulting ontogenetic dynamics of 82 plants in field settings is critically important to improving agricultural production and 83 understanding evolutionary performance.…”

“…Although development typically occurs in a continuous fashion, most studies quantifying 592 development necessarily collect data at discrete timepoints. We take a "parameters as data" 593 approach to FVT modeling to estimate the continuous nature of plant development (Hernandez 594 2015; Kulbaba et al 2017). Much as floral development or leaf development has well defined 595 core molecular genetic pathways that govern organ formation, elaboration, or elongation 596 (reviewed in Bowman et al 2012), there is likely a core genetic architecture that contributes to 597 plant height.…”

Evolution, development, and genetics of floral display—form, size, and arrangement

“…Despite its importance to angiosperm diversification, our knowledge of the evolutionary patterns and the underlying developmental and genetic basis of the floral display is still limited. In the modern times, with the advent of integrating approaches among phylogenetics, ecology, molecular genetics, and development, plant biologists have begun to shed lights on the evolutionary patterns, the underlying driving forces, and the developmental and molecular basis of the floral diversity in some angiosperm lineages (e.g., Gerrath et al, ; Kulbaba et al, ; Liu et al, ; Nikolov & Davis, ; Schrager‐Lavelle et al, ; Zhang et al, ; see review by Ma et al, , this issue).…”

“…Most works presented at the symposium were included in this special issue of Journal of Systematics and Evolution . This issue includes both reviews and research papers reporting works on diverse angiosperm lineages, from dicots (Gerrath et al, ; Kulbaba et al, ; Liu et al, ; Nikolov & Davis, ; Zhang et al, ) to monocots (Schrager‐Lavelle et al, ), from autotrophs (Gerrath et al, ; Kulbaba et al, ; Liu et al, ; Schrager‐Lavelle et al, ; Zhang et al, ) to heterotrophs (Nikolov & Davis, ), and from ecological (Kulbaba et al, ) to morphological and molecular aspects (Gerrath et al, ; Liu et al, ; Nikolov & Davis, ; Schrager‐Lavelle et al, ; Zhang et al, ).…”

“…They emphasized the importance for proper delimitation of characters and character states for understanding floral symmetry evolution since the evolution of floral symmetry can be complicated for particular angiosperm clades. From an ecological aspect, Kulbaba et al () tested the hypothesis that the trait that flowers with variations systematically arranging along inflorescences could be heritable and under selection due to resource competition among flowers. They assessed the various existing techniques of functional data analysis in comparison to their new method using Delphinium glaucum (Ranunculaceae) as a model and demonstrated that their methods are more robust to test the adaptive nature of the systematic trait variation, which was often thought to be due to aspects of development.…”