Influence of geographical isolation and anthropic activities on genetic differentiation of date palm populations in Niger

Abstract Background and Objective: The genetic structuring of populations could be explained by several parameters such as geographical distance and anthropogenic activities. The Niger date palm population is genetically structured into biogeographical distribution of subpopulations; however, it is important to find out the main causes of this structuring. Therefore, this study aims to assess whether this genetic structure is mainly attributable to the constraints related to the distribution of date palm in Niger. Materials and Methods: The matrix of genetic distances (Fst), the matrix of geographic distances, and the anthropic activities matrix (Euclidean distance), between subpopulations were estimated. Mantel's test was used to determine the relationships between these matrices. Indeed, the Mantel test allowed to evaluate the influence of geographic distance matrices and that of the implementation of cultural practices on the matrix of genetic differentiation between subpopulations. The observed variation was compared to the theoretical at 100,000 repetitions for better accuracy. Results: This study showed a significant correlation between the genetic differentiation of subpopulations and the geographical distance between subpopulations (rm = 0.280 and P-value = 0.000) as well as with that of the implementation of cultural practices related to the date palm (rm = 0.534 and P-value = 0.000). The genetic variability between date palm subpopulations can be predicted according to the implementation of the cultural practices adopted by the producers and according to the geographical dispersion of the subpopulations. But the cause-and-effect analysis between genetic distances and geographic distances showed that this relationship is not directly causal, so it’s a spatial autocorrelation. Conclusion: This study is a reference that provides knowledge on the genetic variation between Phoenix dactylifera subpopulations according to anthropic and geographical factors. This serves as information for the sustainable conservation of date palm wealth in Niger.