Agroforestry Trees’ Architecture As Evidence Of Domestication: Case Of African Mango Tree In The Dahomey Gap, West Africa

In tropical Africa, domestication mostly happens across to traditional agroforestry systems, in which natural variations of plants species are constantly manipulated to induce new and more socioeconomically profitable other ones. Irvingia gabonensis (Irvingiaceae) is one of the most valuable sub-Saharan bioresources that widely grow across West and Central Africa. This research evaluates how different sociocultural groups, in the Dahomey Gap (the climatic and vegetation discontinuity inside the Guinean forest continuum), reshape I. gabonensis trees’ architecture in order to adapt this species to their agroforestry needs. Thus, a total of 180 I. gabonensis trees were collected across the Adja, Nago, Fon, and Ewé sociocultural areas and characterized with eight main trees’ architectural factors: number of branches developed, number of sub trees per individual Irvingia tees, level of first large branches insertion on the trunk, crown diameter, leaf width and length, trees’ total height, and crown shape. A Principal Component Analysis was used to classify individual trees and the phylogenetic relationship among them was evaluated by the mean of a Neighbor Joining tree analysis. Trees from the Adja sociocultural group presented the significantly largest crown diameter, the greatest number of branches, the higher number of subtrees the narrower leaves, and the lowest branching pattern.However, local communities did not significantly impact leaf length and trees’ totalheight. Moreover, semicircular crown shape dominated in the Adja sociocultural area, while the broadly pyramidal and pyramidal ones were more represented across other sociocultural areas. These results are indicators of the advance traditional domestication programme led by the Adja community since decades, as the only opportunity to develop profitable productive systems across the exhausted lands this community populate. Irvingia gabonensis population in this area represent an important gene bank, valuable for intensive cultivation in West and Central Africa