A predicted developmental and evolutionary morphospace for grapevine leaves

Abstract

Using conventional statistical approaches there exist powerful methods to classify shapes. Embedded in morphospaces is information that allows us to visualise theoretical leaves. These unmeasured leaves are never considered nor how the negative morphospace can inform us about the forces responsible for shaping leaf morphology. Here, we model leaf shape using an allometric indicator of leaf size, the ratio of vein to blade areas. The borders of the observable morphospace are restricted by constraints and define an orthogonal grid of developmental and evolutionary effects which can predict the shapes of possible grapevine leaves. Leaves in the genus Vitis are found to fully occupy morphospace available to them. From this morphospace, we predict the developmental and evolutionary shapes of grapevine leaves that are not only possible, but exist, and argue that rather than explaining leaf shape in terms of discrete nodes or species, that a continuous model is more appropriate.

Replicated radiations in the South American marsh pitcher plants (Heliamphora) lead to convergent carnivorous trap morphologies

“…Unoccupied regions in the space of possible phenotypes are often attributed to constraints on evolution, be they structural, ecological, or developmental (e.g., Vernescu and Ryser, 2009; Stayton, 2019; Chitwood and Mullins, 2022]. We observed several gaps in pitcher space represented the absence of certain trait combinations, such as large and curvy pitchers or small and slender pitchers.…”

A high resolution model of the grapevine leaf morphospace predicts synthetic leaves

“…Previously, using thousands of leaves with only 21 landmarks (Chitwood and Mullins, 2022), we 466 similarly sampled the Vitis morphospace as we have done here. Consistent between both 467 works, genetic and developmental contributions to leaf shape are orthogonal and can be 468 predicted independently of the other.…”

“…Yet, because we can estimate developmental variation in relation to variation that defines differences between species and varieties ( Figs. 4-6 ), we look forward to predicting developmental series of wine and table grape varieties and comparing them to empirically sampled leaves, as we previously proposed (Chitwood and Mullins, 2022). Another possibility is to bypass manual measurements by projecting onto a precalculated morphospace.…”

“…We next created continuous developmental models of leaf shape, modeling each x and y coordinate value as a polynomial function of node position in the shoot and using the resulting "composite" leaf shapes to show that they discriminate species identity better than individual leaves (Bryson et al, 2020). Using 21 landmarks on the Geneva leaves and in comparison to V. vinifera leaves derived from California breeding populations, we calculated a morphospace: a continuous representation that can be used to visualize and demarcate the extent of genetic, developmental, and environmental variation in the genus Vitis (Chitwood and Mullins, 2022). The above studies rely on a small number of homologous landmark points to represent leaf shape.…”

Replicated radiations in the South American Marsh Pitcher genus Heliamphora (Sarraceniaceae) lead to convergent carnivorous trap morphologies

“…Unoccupied regions in the space of possible phenotypes are often attributed to constraints on evolution, be they structural, ecological or developmental (e.g. (Vernescu and Ryser 2009;Stayton 2019;Chitwood and Mullins 2022)). We observed several gaps in pitcher space represented the absence of certain trait combinations, such as large and curvy pitchers or small and slender pitchers.…”