Abstract
Understanding patterns of genetic diversity of plants is important in guiding conservation programs. The aim of our study was to characterize genetic diversity in Afzelia quanzensis, an economically important African tree species. We genotyped 192 individuals at 10 nuclear microsatellite loci. Samples were collected from nine sites in Zimbabwe, five in the north and four in the south, separated by a mountain range, the Kalahari-Zimbabwe axis. Overall, genetic diversity was relatively low across all sites (expected heterozygosity (H E) = 0.452, mean number of alleles (A) = 4.367, allelic richness (A R) = 2.917, effective number of alleles (A E) = 2.208, and private allelic richness (PAR) = 0.197). Genetic diversity estimates, H E, A, A R, and PAR, were not significantly different between northern and southern sites. Allelic richness was significantly higher in southern sites. Significant population differentiation was observed among all sites (F ST = 0.0936, G′ ST = 0.1982, G ST = 0.1001, D JOST = 0.0598). STRUCTURE analysis and principal components analysis identified two gene pools, one predominantly made up of southern individuals, and the other of northern individuals. A Monmonier’s function detected a genetic barrier that coincided with the Kalahari-Zimbabwe axis. The relatively low level of genetic diversity in A. quanzensis may reduce adaptability and limit future evolutionary responses. All sites should be monitored for deleterious effects of low genetic diversity, and genetic resource management should take into consideration the existence of the distinct gene pools to capture the entire extant genetic variation.
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Acknowledgements
We thank J. Backs and reviewers of the journal Tree Genetics and Genomes for comments on the manuscript. Appreciation goes to N. Mlotshwa, Z. Sibanda and S. Ndlovu, of the Forestry Commission of Zimbabwe, for helping with sampling and identification of individuals. Appreciation goes to K. Feldheim, of the Pritzker Laboratory for Molecular Systematics and Evolution at The Field Museum of Natural History, for facilities and equipment.
Funding
This work was supported by Fulbright through the Institute of International Education, and the Office of International Affairs at the University of Illinois at Chicago through the Chicago Consular Corps Scholarship.
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Jinga, P., Ashley, M.V. A mountain range is a strong genetic barrier between populations of Afzelia quanzensis (pod mahogany) with low genetic diversity. Tree Genetics & Genomes 14, 4 (2018). https://doi.org/10.1007/s11295-017-1217-x
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DOI: https://doi.org/10.1007/s11295-017-1217-x