Analysis of Morphological Variability in Five Spontaneous Populations of Rubus ulmifolius Schott in Tunisia

Abstract

Aim: To study the morphological variability among Rubus ulmifolius Schott populations, a comparative analysis was undertaken in five wild populations grown under different climatic conditions in Tunisia. Study Design: Morphological characterization using 10 quantitative traits concerning the morpho-metrical aspect of the shrub, the leaves and the inflorescences of 5 spontaneous populations of Rubus ulmifolius Schott. Place and Duration of Study: The provinces of Beja, Bizerte and Jendouba, Tunisia in June 2011. Methodology: Morphological traits were measured and evaluated separately on a representative population of shrub, leaf and inflorescence. For each site, we made fifteen individual measurements. A sample of one shrub, twenty adult leaves and four inflorescences per plant were evaluated and measured. Samples were collected from fifteen mother shrubs per population, that were separated from each other by more than 20 m to minimize the risk of sampling closely related individuals. Results: The ANOVA analysis as well as mean comparison of the morphological traits revealed a significant (P < 0.01) diversity for the majority of examined descriptors except, the number of flowers NFL (P=0,142) and the number of leaflets NF (P=0,119) which were not significantly different within and among the populations. Furthermore, in the multivariate analysis, the populations were separated into three different groups through the discriminating variables: Height of the shrub, leaf dimensions, weight of dry matter, height and weight of the inflorescence. Conclusion: The morphological variability exhibited by the Tunisian populations of Rubus ulmifolius Schott may be interpreted as relevant to the ecological plasticity and the physiological mechanisms. If Rubus morphology is partially due to environment, the divergences observed between these genetically differentiated populations suggest that the genetic systems that involve these phenotypes are under selection in the concerned environments. So adaptive morphological changes observed in these populations reveal probably the progress of evolutionary phenomena within Rubus ulmifolius Schott.