Geometric morphometric analyses of leaf variation in four oak species of the subgenus Quercus (Fagaceae)

Abstract

This paper defines a protocol for the study of leaf morphology and morphometric relationships among Quercus frainetto, Quercus robur, Quercus petraea and Quercus pubescens. Leaf shapes were investigated in an attempt to characterize and discriminate among these four species. Landmark and outline data were compared in order to ascertain their relative efficacy for describing variation in leaf morphology. MANOVA was performed to assess intra‐specific differentiation and to compare the distribution of variance in individuals, populations and species. A strong correlation was found between landmark and outline datasets of the four species: both methods proved capable of discriminating among the four species. Finally, a Two‐Block Partial Least‐Squares analysis was performed for each species in order to assess the correlation between intra‐specific shape variation and environmental factors.

Keywords:

• Geometric morphometrics
• landmarks
• leaf shape
• multivariate outliers
• outlines
• Quercus
• Two‐Block Partial Least‐Squares analysis

Acknowledgements

The authors would like to dedicate this work to the memory of Marco Corti (1950–2007), leader of the Italian geometric morphometrics school. The research was partially financed with a contribution PRIN 2005 n.2005072945 “Landscape transformations in Molise: analysis of agri‐environment dynamics”.