Inter- and intraspecific variability of Quercus cerris L. and Quercus frainneto Ten. in the Šumadija region (Serbia) based on leaf geometric morphometrics

In this study, we used leaf geometric morphometrics to quantify the differences among Quercus cerris L. and Quercus frainetto Ten. and their populations in the Šumadija region in Serbia. We sampled 2200 leaves from eight populations and on each leaf recorded 13 landmarks. To analyze how leaf morphology varies across species and populations, we used Procrustes ANOVA, a two-block partial least-squares analysis, a principal component analysis and a canonical variate analysis. The results showed a clear discrimination between species, followed by different levels of leaf shape variability in Q. cerris and Q. frainetto. The leaves of Q. cerris displayed higher levels of variability and higher differences among populations compared to Q. frainetto. The patterns of population grouping in the two species greatly differed, indicating that in these species different factors contribute to intraspecific variability. This study provides preliminary results of the leaf morphometric variability of oak species in the Šumadija region in Serbia. Future studies should include genetic and environmental analyses to understand the origins of phenotypic differences between species and populations, and to fully recognize which factors mostly determine relationships between taxa.