Mejía de Loayza, EduardoEstivals, GuillainCastro Ruiz, DianaChota Macuyama, WernerAngulo Chávez, CarlosCorazon Guivin, MikeRodríguez del Castillo, Ángel MartínAlvarado Reategui, JhonAngulo Villacorta, CarlosMejía, KemberDel Castillo Torres, DennisGarcía Dávila, Carmen2026-06-042026-06-042026-03-27Mejia de Loayza, E., Estivals, G., Castro-Ruiz, D., Chota-Macuyama, W., Angulo-Chavez, C., Corazon-Guivin, M., Rodriguez del Castillo, Á., Alvarado Reategui, J., Angulo-Villacorta, C., Mejia, K., Del Castillo Torres, D., & García-Dávila, C. (2026). Genetic diversity and population structure of Myrciaria dubia from the Peruvian Amazon: Implications for germplasm conservation and crop improvement. Genetic Resources and Crop Evolution, 73, 159. https://doi.org/10.1007/s10722-026-02787-80925-9864http://hdl.handle.net/20.500.12955/3147Myrciaria dubia (camu-camu) is a shrubby fruit tree native to the continental Amazon whose fruits have been intensively harvested from wild stands, potentially reducing effective population sizes. We quantified genetic diversity and population structure across seven wild Peruvian Amazon populations and delineated river-basin genetic units to guide provenance-aware germplasm conservation and breeding. We genotyped 254 individuals from the Napo, Ucayali, Nanay, Tahuayo, Putumayo, Tigre, and Curaray basins using six polymorphic microsatellite loci. Overall, 48 alleles were detected. Observed heterozygosity (0.149–0.483) was generally lower than expected heterozygosity (0.220–0.531), and population-level inbreeding coefficients (FIS=−0.038– 0.560) indicated significant heterozygote deficits in Napo, Curaray, and Tahuayo. The Putumayo population harbored nine private alleles, representing a unique genetic reservoir. Pairwise differentiation was substantial (FST=0.093–0.660; Nei’s distance=0.068–1.734), with the strongest divergence between Tigre and Ucayali. Neighbor-joining, Bayesian assignment, and Discriminant Analysis of Principal Components (DAPC) initially supported three major genetic units and highlighted Putumayo as genetically isolated; additionally, hierarchical STRU CTURE analyses resolved eight clusters, and DAPC distinguished seven population-specific groups. Analysis of molecular variance attributed 56.5% of the variation within individuals and 34.7% among populations. Mantel tests supported isolation by distance based on straight-line geographic distances (r=0.53– 0.56; p≤0.017), whereas river-network distances were not significant. Overall, the data indicate a geographically structured genetic architecture shaped by dispersal limitation and basin-scale differentiation, supporting three provenance units for germplasm banking and breeding: (i) Napo–Ucayali–Nanay– Tahuayo, (ii) Tigre–Curaray, and (iii) Putumayo.application/pdfenginfo:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by/4.0/Conservation geneticsGenética de la conservaciónGene flowFlujo genéticoPopulation structureEstructura poblacionalMicrosatellite markersMarcadores microsatéliteMolecular markersMarcadores molecularesinfo:eu-repo/semantics/articlehttps://purl.org/pe-repo/ocde/ford#4.01.00https://doi.org/10.1007/s10722-026-02787-8Genetic diversity; Diversidad genética (recurso); Germplasm; Germoplasma; Resource conservation; Conservación de los recursos; Population genetics; Genética de poblaciones; Wetlands; Tierra húmeda; River basins; Cuenca fluvial