Floral Morphology inNicotiana: Architectural and Temporal Effects on Phenotypic Integration

Patterns of phenotypic correlations among morphological traits across plants and animals

“…Floral correlations lower than vegetative correlation could be caused by modularity within the flower, as there may be within the vertebrate head, but few studies to date have addressed within-flower modularity. The study of Bissell & Diggle [19] is a notable exception; their study included an unusually large number of floral traits (17), and this level of trait sampling is likely necessary to uncover within-flower modularity.…”

Modularity and intra-floral integration in metameric organisms: plants are more than the sum of their parts

“…One potential explanation for the marked heterogeneity among taxa in levels of integration, and the unexpectedly weak integration observed in the flowers of some taxa, is that flowers are not single fully integrated units. Rather, the multiple functions of the flower are each performed by distinct suites of integrated characters that share a common function but are independent of sets of structures with alternative functions, that is, floral variation/covariation may be modular [46][47][48][49]. Independence among functional modules would reduce measures of overall integration for the flower as a whole.…”

“…Similarly, analyses of modularity highlight those features that develop independently. For example, regions of the corollas of Nicotiana show three contrasting patterns of variation and covariation [48]. The corolla tube above the point of stamen attachment forms part of the efficiency module and covaries with the stamen and gynoecium while the flared region of the same corolla is included in the attraction module and varies independently of the tube.…”

“…Conversely, if individual floral traits vary independently with respect to architecture, then this will disrupt integration and patterns of covariation may differ among the flowers of the same plant. In Nicotiana alata and N. forgetiana, the species described in the preceding section as having distinct and independent efficiency and attraction modules, there are significant architectural effects on overall flower size: flower size declines with position within an inflorescence and among successive inflorescences [48]. Despite this size variation, the identity of the particular traits included in the intra-floral modules (efficiency module and attraction module), integration of traits within each module, and independence between the modules, is maintained.…”

Plasticity and within plant sex-ratio variation in monoecious Emex spinosa

“…This indicates the importance of analyzing plastic responses in plants not only as integrated systems but also as developmental systems constituted by numerous modules. It is well known that sex expression can be related to plant size, age, or position (Armbruster, 1991;Bissell and Diggle, 2008;Mancuso and Peruzzi, 2010;Zhao, 2010). In fact, the variability of reproductive traits along plants axis had been previously studied in Emex spinosa (Ortiz et al, 2009), and we will discuss whether this variability is also affected by light intensity.…”