Quantitative genetics of developmental stability in flower traits of <i>Solanum rostratum</i>

In modular species such as flowering plants, developmental stability estimated as the within-individual variation, is a property of the genotype. This implies that the regulatory mechanisms through which environmental factors shape the phenotype during ontogeny could be heritable and potentially evolve by natural selection. This study provides experimental evidence of the potential response to selection of flower developmental stability by estimating the additive genetic (co)variance matrix of within-individual variation of morphometric flower traits and testing its evolutionary potential in a natural population. We employed a partial diallel crossing design, growing plants of the annual Solanum rostratum under controlled greenhouse conditions. Our phenotypic variance partitioning analysis showed significant additive genetic within-individual variances and covariances for some, but not all, floral traits. Multivariate analysis showed a lower number of significant additive genetic covariances for the within-individual variation compared with genotypic means. For those traits with significant additive genetic variation, we found that within-individual variation exhibited higher evolvability compared with genotypic means. These differences in the G-matrix components suggest that the genetic architecture responsible for the expression of means and variances may not be entirely shared. Although this aligns with available genomic evidence for plants, there is not yet available for the floral traits presented here. Overall, the evidence presented in this study indicates that unlike genotypic means, the evolvability of the developmental stability in morphometric flower traits is primarily constrained by the magnitude of additive genetic variance, rather than to the limited number of additive genetic covariances.