Abstract
Ten fruit and kernel traits were measured in 152 Irvingia gabonensis and 293 Dacryodes edulis trees from 6 villages in Cameroon and Nigeria. Frequency distribution curves were used to examine the range of variation of each trait of each species in each village and aggregated into national and regional populations. There were differences between the village sub-populations, with regard to the normality (e.g., mean kernel mass of D. edulis) or skewness (e.g., mean flesh depth of D. edulis) of the distribution curves and in the degree of separation between the individual village populations along the x axis, resulting in the development of a bimodal distribution in the regional population. For all traits, populations of both species differed significantly between countries, but only in D. edulis were there significant differences between the Cameroon populations. On the basis of the results of this study, D. edulis can be said to be virtually wild in Nigeria but semi-domesticated in Cameroon, while I. gabonensis is wild in Cameroon and semi-domesticated in Nigeria. These results are discussed with regard to a hypothesis that the range and frequency of variation in the different populations can be used to identify five stages of domestication. From a comparison of the frequency distribution curves of desirable versus undesirable traits, and statistically identifyable changes in skewness and kurtosis, it is concluded that as a result of the farmers’ own efforts by truncated selection, D. edulis is between Stages 2 and 3 of domestication (with a 67% relative gain in flesh depth) in Cameroon, while I. gabonensis in Nigeria is at Stage 2 (with a 44% relative gain in flesh depth). In this study, genetic diversity seems to have been increased, and not reduced, by domestication.
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References
Anegbeh P.O., Usoro C., Ukafor V., Tchoundjeu Z., Leakey R.R.B. and Schreckenberg K. in press. Domestication of Irvingia gabonensis: 3. Phenotypic variation of fruits and kernels in Nigeria. Agroforestry Systems 58: 213-218.
Anegbeh P.O., Ukafor V., Usoro C., Tchoundjeu Z., Leakey R.R.B. and Schreckenberg K. 2002. preprint. Variation in fruit traits of Dacryodes edulis in Nigeria: opportunities for selection.
Atangana A.R., Tchoundjeu Z., FondounJ-M., Asaah E., Ndoumbe M. and Leakey R.R.B. 2001. Domestication of Irvingia gabonensis: 1. Phenotypic variation in fruit and kernels in two populations from Cameroon. Agroforestry Systems, 53: 55–64.
Atangana A.R., Ukafor V., Anegbeh P.O., Asaah E., Tchoundjeu Z., Usoro C., Fondoun J-M., Ndoumbe M. and Leakey R.R.B. 2002. Domestication of Irvingia gabonensis: 2. The Selection of multiple traits for potential cultivars from Cameroon and Nigeria. Agroforestry Systems, 55: 221–229.
Bani-Aameur F., Ferradous A. and Dupuis P. 1999. Typology of fruits and stones of Argan spinosa (Sapotaceae). Forest Genetics, 6, 213–219.
Futuyma D.J. 1998. Evolutionary Biology (3rd Edition), Sinauer Associates, Sunderland, Massachusetts, USA, 763 p.
Genstat 5 Committee of the Statistics Department, Rothamsted Experimental Station 1993. Genstat 5, Release 3 Reference Manual. Oxford: Clarendon Press.
Ladipo D.O., Fondoun J-M. and Ganga N. 1996. Domestication of the bush mango (Irvingia spp.) some exploitable intraspecific variations in west and central Africa, In: Leakey R.R.B., Temu A.B., Melnyk M. and Vantomme P. (Eds.), Domestication and Commercialization of Non-Timber Forest Products in Agroforestry Systems, Non-Wood Forest Products, No 9, FAO, Rome, Italy, pp. 193–205.
Leakey R.R.B. 2001a. Win:Win landuse strategies for Africa: 1. Building on experience with agroforests in Asia and Latin America, International Forestry Review, 3, 1–10.
Leakey R.R.B. 2001b. Win:Win landuse strategies for Africa: 2. Capturing economic and environmental benefits with multistrata agroforests. International Forestry Review, 3, 11–18.
Leakey R.R.B. and Simons A.J. 1998. The domestication and commercialization of indigenous trees in agroforestry for the alleviation of poverty. Agroforestry Systems, 38, 165–176.
Leakey R.R.B., Fondoun J-M., Atangana A. and Tchoundjeu Z. 2000. Quantitative descriptors of variation in the fruits and seeds of Irvingia gabonensis. Agroforestry Systems, 50, 47–58.
Leakey R.R.B., Atangana A.R., Kengni E., Waruhiu A. N., Usuro C., Anegbeh P.O. and Tchoundjeu Z. 2002. Domestication of Dacryodes edulis in West and Central Africa: Characterisation of Genetic Variation. Forests, Trees and Livelihoods, 12: 57–72.
Mbosso M.F.P.C. 1999. Opportunités et contraintes socioéconomiques liées à la culture des arbres fruitiers locaux dans les basses terres humides du Cameroun: Dacryodes edulis et Irvingia gabonensis. Mémoire de fin d'études présenté pour l'obtention du diplome d'Ingenieur Agronome, Université de Dschang, 111 p.
McNeely J.A. and Scherr S.J. 2001. Saving our Species: How the Earth's Biodiversity Depends on Progress in Agriculture. Future Harvest, Washington DC, USA.
Patterson H.D. and Thompson R. 1971. Recovery of inter-block information when block sizes are unequal. Biometrika 58: 545–554.
Ruiz Pérez M., Ndoye O. and Eyebe A. 1999. Marketing of nonwood forest products in the humid forest zone of Cameroon. Unasylva, 50 (198), 12–19.
Schreckenberg K., Degrande A., Mbosso C., Boli Baboulé Z., Boyd C., Enyong L., Kanmegne J., and Ngong C. 2002. The social and economic importance of Dacryodes edulis (G.Don) H.J. Lam in southern Cameroon. Forests, Trees and Livelihoods 12: 15–40.
Serageldin I. and Persley G.J. 2000. Promethean Science: Agricultural Biotechnology, the Environment, and the Poor. CGIAR, 1818 H St, Washington, DC 20433, USA, 41 pp.
Shiembo P.N., Newton A.C. and Leakey R.R.B. 1996. Vegetative propagation of Irvingia gabonensis Baill., a West African fruit tree. Forest Ecology and Management, 87, 185–192.
Simons A.J. 1996. ICRAF's strategy for domestication of non-wood tree products, In: Leakey R.R.B., Temu A.B., Melnyk M. and Vantomme P. (Eds.), Domestication and Commercialization of Non-Timber Forest Products in Agroforestry Systems, Non-Wood Forest Products, No 9, FAO, Rome, Italy, pp. 8–22.
Stearns S.C. and Hockstra R.F. 2000. Evolution: An Introduction, Oxford University Press, Oxford, England, 381 p.
Tchoundjeu Z., Duguma B., Fondoun J.-M. and Kengue J. 1998. Strategy for the domestication of indigenous fruit trees of West Africa: case of Irvingia gabonensis in southern Cameroon. Cameroon Journal of Biology and Biochemical Sciences, 4, 21–28.
Wald W. 1940. A note on the analysis of variance with unequal class frequencies. Annals of Mathematical Statistics 11: 96.
Waruhiu A.N. 1999. Characterization of fruit traits towards domestication of an indigenous fruit tree of west and central Africa: A case study of Dacryodes edulis in Cameroon, MSc Thesis, University of Edinburgh, 58 pp.
Zobel B.J. and Talbert J.T. 1984. Applied Forest Tree Improvement, John Wiley & Sons, New York, USA, 505 p.
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Leakey, R.R., Tchoundjeu, Z., Smith, R.I. et al. Evidence that subsistence farmers have domesticated indigenous fruits (Dacryodes edulis and Irvingia gabonensis) in Cameroon and Nigeria. Agroforestry Systems 60, 101–111 (2004). https://doi.org/10.1023/B:AGFO.0000013259.95628.22
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DOI: https://doi.org/10.1023/B:AGFO.0000013259.95628.22