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Abstract
Abstract
Background: Leaf shape among Passiflora species is spectacularly diverse. Underlying
this diversity in leaf shape are profound changes in the patterning of the primary
vasculature and laminar outgrowth. Each of these aspects of leaf morphology—vasculature
and blade—provides different insights into leaf patterning.
Results: Here, we morphometrically analyze >3300 leaves from 40 different Passiflora
species collected sequentially across the vine. Each leaf is measured in two different
ways: using 1) 15 homologous Procrustes-adjusted landmarks of the vasculature, sinuses,
and lobes; and 2) Elliptical Fourier Descriptors (EFDs), which quantify the outline
of the leaf. The ability of landmarks, EFDs, and both datasets together are compared
to determine their relative ability to predict species and node position within the
vine. Pairwise correlation of x and y landmark coordinates and EFD harmonic coefficients
reveals close associations between traits and insights into the relationship between
vasculature and blade patterning.
Conclusions: Landmarks, more reflective of the vasculature, and EFDs, more reflective
of the blade contour, describe both similar and distinct features of leaf morphology.
Landmarks and EFDs vary in ability to predict species identity and node position in
the vine and exhibit a correlational structure (both within landmark or EFD traits
and between the two data types) revealing constraints between vascular and blade patterning
underlying natural variation in leaf morphology among Passiflora species.