The evolution of floral ontogenetic allometry in the Andean genus Caiophora (Loasaceae, subfam. Loasoideae)

Abstract

The astounding variety of angiosperm flower morphologies has evolved in response to many selective forces. Flower development is highly coordinated and involves developmental associations between size and shape, ontogenetic allometry, which in turn affect the morphology of mature flowers. Although ontogenetic allometries can act as a developmental constraint and may influence adaptive evolution, allometries can evolve themselves and may change rapidly in response to selection. We explored the evolution of ontogenetic allometry in the flowers of 11 species of Loasoideae. Seven species belong to Caiophora, which radiated recently in the central Andes, and contains species that are pollinated by bees, hummingbirds, and small rodents.According to a previous study, the diversification of Caiophora involved departures from simple allometric scaling, but the changes to allometry that enabled flower diversification have not been explored yet. We characterized the ontogenetic allometry of each species with the methods of geometric morphometrics. We studied the evolution of allometries by constructing allometric spaces, in which the allometry of each species is represented by a point and the arrangement of points indicates the relations among allometric trajectories. To examine the history of changes of ontogenetic allometries, we projected the phylogeny into the allometric spaces. Inspection of allometric spaces suggests that ontogenetic variation is limited to a few dominant features. The allometries of the two main functional flower parts under study differ in their evolutionary labilities, and patterns of variation reflect pollination systems, differences in structural organization, and abiotic environmental factors.

Chrysomya megacephala (Fabricius, 1794) (Diptera: Calliphoridae) development by landmark-based geometric morphometrics of cephalopharyngeal skeleton: a preliminary assessment for forensic entomology application

“…By using regression analysis of the Procrustes coordinates and centroid size/log-transformed centroid size, the association between shape and size across different age groups was significant with moderate to high effect. This allometric effect has been reported in other organisms and the relationships vary and were usually high during ontogenesis (Rocha et al 2005;Scalici et al 2010;Strelin et al 2018). However, for future studies, we recommend using an equal amount of sample size between groups and to reassess the GM landmarks.…”

Evolution of multivariate wing allometry in schizophoran flies (Diptera: Schizophora)

“…The vectors of coefficients of these regressions represent the multivariate ‘broad‐sense’ form of static allometry for each sex and species, respectively. These allometric vectors (A) were then used to compute allometric spaces using ordination of allometric vectors to illustrate variation in allometric scaling (Gerber, Eble, & Neige, 2008; Gerber & Hopkins, 2011; Strelin, Benitez‐Vieyra, Fornoni, Klingenberg, & Cocucci, 2018). To this end, I used the R‐function prcomp() based on the covariance matrix of all static allometric vectors.…”

Use and misuse of discrete character data for morphospace and disparity analyses

“…This construction has been referred to as ‘phylomorphospace’ (Sidlauskas ; but see Strelin et al . for a warning regarding the use of this term). It has been used to infer the placement of ‘ancestors’ in the morphospace, assess the strength of the phylogenetic signal contained in a morphological dataset, and test for patterns of convergence (e.g.…”