Conservation genetics of bush mango from Central/West Africa: implications from random amplified polymorphic DNA analysis

Genetic variation was assessed in the two bush mango species, Irvingiagabonensis and I.wombolu, valuable multipurpose fruit trees from central and west Africa that are currentlyundergoing domestication. A total of 130 individuals sampled from Cameroon, Nigeriaand Gabon were analysed using 74 random amplified polymorphic DNAs (RAPDs).Significant genetic integrity was found in the two morphologically similar species (among-species analysis of molecular variance [AMOVA] variance component 25.8%, P < 0.001), withno evidence of hybridization, even between individuals from areas of sympatry wherehybridization was considered probable. Results suggest that large-scale transplantationof either species into new habitats will probably not lead to genetic introgression from orinto the other species. Therefore, subsequent cultivation of the two species should not behindered by this consideration, although further studies on the potential for hybridization/introgression between these species would be prudent. Significant genetic differenti-ation of both species (among-countries within species, nested AMOVA variance component9.8%, P < 0.001) was observed over the sampled regions, and genetic similarity of samplesdecreased significantly with increasing geographical distance, according to number ofalleles in common (NAC) analysis. ‘Hot spots’ of genetic diversity were found clusteredin southern Nigeria and southern Cameroon for I. wombolu, and in southern Nigeria,southern Cameroon and central Gabon for I. gabonensis. The possible reasons for thisdistribution of genetic variation are discussed, but it may reflect evolutionary history, asthese populations occur in areas of postulated Pleistocene refugia. The application ofthese results to domestication programmes and, in the light of extensive deforestation inthe region, conservation approaches, is discussed.

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DOI:

https://doi.org/10.1046/j.1365-294x.2000.00936.x

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