The frequency of secondary branches, which provides for supplementary spikelet sites if resources allow them, was the most variable trait of panicle architecture.
Assuming any trait was affected by only a single mutation and that each pleiotropic mutation affected equal numbers of traits (i.e., all modules are the same size), let m be the number of variational modules and n be the number of traits in a module, so that m × n = 3384 (one less than the number of variable traits to allow for bivariate sampling).
We further characterized mutational pleiotropy in the 3385 variable traits, using sets of 5, randomly assigned, traits.
The CGH-approach has also been used to evaluate the dissemination of variable traits from the V583 genome within diverse lineages of the species [ 17].
Also, the key concepts that are required to understand biological evolution are simple, and students need only to recognize: (1) the existence of intra-specific variability; (2) that part of this variability can be transmitted over generations; (3) that the frequency of variable traits may change over generations; and (4) that these changes may cause the emergence of distinct species over time.
For the expression trait set analyzed here, an average variational module size of 70 corresponds to effects on 0.6% of all expression traits, or 2.1% of variable traits, at the lower range reported for null mutations.
Each of the 3385 variable traits was assigned to one of 677 five-trait sets.
Sampling 6768 (0.1%) of the possible >5.7 × 10 bivariate pairs of variable traits, we found 35 significant (FDR < 0.05) covariances.
In addition, floral and vegetative morphology of Magnoliidae is highly variable and several of these variable traits have been shown to be associated with variation of diversification rates in other flowering plant lineages [ 10].
Mutations affecting gene expression were predominantly of small phenotypic effect, with only ∼8% of mutationally variable traits affected by a mutation with an effect size of >1 phenotypic standard deviation.
