Jepkemboi , Sylvia2025-07-122025-07-122023-05https://ir-library.ku.ac.ke/handle/123456789/30623Ir\:ingiu is a genus of trees in the Irvingiaceae family endemic to West Africa, Central Al and Southeast Asia. Two closely related species; Irvingia gabonensis and (: vingia wombolu are indigenous to West and Central Afiica and are of high economic importance owing to their valuable kernels. They grow wild in tropical forests and are also -planlcd in agroforestry systems as windbreaks near coffee plantations. The two species are commonly referred to as bush mango which have several uses in various fields such as, traditional medicine, drug adjuncts, weight loss, cloth dye, food, cosmetics, timber and firewood. Local communities consume bush mango kernels with their day-to-day food and also trade them in local and international markets. This has led to massive fruit collection and subsequent decline in regeneration leading to potential loss of genetic diversity. Conservation of these species is imperative in order to avoid genetic erosion in the wild and to maintain a sustainable use in agroforestry. The main objective of this study was to evaluate the genetic diversity and population structure of Irvingia species; I gabonensis, I. wombolu and I. robur using single nucleotide polymorphisms (SNPs) markers of accessions from Nigeria, Cameroon and Gabon held at the Word Agroforestry (International Center for Research in Agroforestry, ICRAF) field genebanks. Diversity arrays technology with sequencing (DArTseq) was used to discover SNPs in DNA samples representing 340 Irvingia accessions. The SNPs were used to determine the measures of genetic diversity, analysis of molecular variance (AMOVA) and population structure using various software; GenAlEx, Arlequin, MSA, PHYLIP, and STRUCTURE. 3,170 SNPs revealed a relatively low genetic diversity in accessions held at the ICRAF genebank as shown by the gene diversity (He = 0.24) and proportion of polymorphic loci (P = 63.28%). Populations from Cameroon and Nigeria had the highest genetic diversity than Gabon. AMOVA indicated that much of the genetic variation was preserved within individuals (70%) while low variations existed among individuals and among populations, 19% and 11% respectively. Cluster analyses by STRUCTURE and Neighbor Joining tree showed a close relationship of I gabonensis accessions from Cameroon with Nigeria and Gabon. Nigerian and Gabonese . gabonensis accessions were rarely clustered together, suggesting differentiation by evolution. Most I wombolu and I robur accessions clustered separately from I. gabonensis although some 1. wom_bvlu were mixed with /, gabonensis accessions thus showing some extent of species delineation. Cluster analyses were consistent with Principal coordinates analysis (PCoA). Collection of more seeds from natural forests of Cameroon and Nigeria should be considered for the enrichment of genetic diversity of current collections at ICRAF genebanks. The wider geographic range of bush mango should also be represented in the genebanlg to capture a broader genotypic diversity. DArTseq basec! SNPs are suitable for‘ genetic dlvers_uy analysis in /rvingia, and the highly polymorphic markers can be'l‘\sed in future breeding studies of bush mango for nutrition, yield and environmental resilience.enThesis