Leaf morphological analyses in four European oak species (Quercus) and their hybrids: A comparison of traditional and geometric morphometric methods

Abstract

In this study, leaf morphology was assessed in a mixed oak stand (western France) using two geometric morphometric (landmark and outline) datasets and one dataset of 19 leaf measures. Adult oaks (817 oaks), comprising four white oak species (Quercus petraea, Q. robur, Q. pubescens and Q. pyrenaica), were sampled for DNA extraction and genetic analysis (nuclear microsatellites). Leaf morphology was assessed on 336 oaks, comprising pure species and hybrids as determined by genetic assignment. This comparative study of oak leaf morphology, based on the use of two free size geometric morphometric methods and a set of leaf measurements, combined with the genetic assignment of individuals to pure species or hybrids, provided information about the differences among species and the intermediate leaf morphology of their hybrids.

Keywords:

• Genetic assignment
• hybridization
• traditional morphometrics
• geometric morphometrics
• leaf morphology
• nuclear microsatellites
• Quercus

Acknowledgements

We thank Jérôme Willm and Guy Roussel for help in collecting leaves and Florian Alberto for leaf measurements. Genotyping was performed at the Genotyping and Sequencing facility of Bordeaux (grants from the Conseil Régional d’Aquitaine no. 20030304002FA and 20040305003 FA and from the European Union, FEDER no. 2003227).