Climate-induced morphological variation of black plum (Vitex doniana Sw.) in Benin, West Africa

There are evidences that plant morphology is shaped by genotype, but local environment mainly climate influences morphology as well. In this study the morphological variability of Vitex doniana, a multipurpose tree species was characterised in relation with climatic parameters in order to provide insights to the species possible responses to future climate change. Morphological data were collected on 102 trees randomly selected along unfixed transects in the three climatic zones of Benin. Data were collected on fruiting trees at three levels: tree (trunk and canopy), leaves and fruits. Variance components were estimated for identification of variability sources regarding leaves and fruits characteristics. The most important discriminant descriptors regarding climatic zones were selected through a stepwise discriminant analysis. Relationship between those discriminant morphological traits and bioclimatic variables were assessed through a redundancy analysis. Our findings confirmed that there is an important variability of morphological traits of the species and climate, mainly some of its extremes parameters plays a non-negligible role. Trees in the Sudanian region are the biggest with fruits producing little pulp while individuals in the more humid Guinean region present a higher amount of pulp whereas Sudano-Guinean trees are the tallest with larger leaves. Although the climate-induced variability of the species is relatively low, the study gives insights in probable effects of climate variability on its morphology. Population genetic studies are required for a better understanding of climatic impacts on V. doniana in order to develop selection and domestication schemes which could contribute to its conservation.