International Journal of Molecular Evolution and Biodiversity 2024, Vol.14, No.3, 120-132 http://ecoevopublisher.com/index.php/ijmeb 121 single-copy nuclear gene glyceraldehyde 3-phosphate dehydrogenase (G3pdh) and microsatellite loci have provided insights into the crop’s evolutionary origin, suggesting that the domestication of cassava did not involve multiple progenitor species or hybridization with closely related species such as Manihot pruinosa (Olsen and Schaal, 1999). Genetic evidence further supports the southern Amazonian origin of domestication, with phenetic analyses grouping cassava with wild populations from this region (Olsen and Schaal, 2001). 1.2 Domestication timeline The timeline of cassava’s domestication has been a subject of extensive research. Phylogenomic analyses indicate that the genus Manihot, to which cassava belongs, diversified around 6 million years ago, with cassava’s domestication occurring much later, and found different taxa are morphologically diverse (Figure 1) (Simon et al., 2021). The genetic variation in cassava is a subset of that found in the wild M. esculenta subspecies, indicating that the crop was derived solely from its conspecific wild relative (Olsen and Schaal, 2001). The differentiation among wild populations is likely a result of random genetic drift following recent population divergence, which suggests a relatively recent domestication event (Olsen and Schaal, 2001). Comparative genotyping of Brazilian cassava germplasm has also provided insights into the diversification and domestication of cassava, revealing spatial genetic differentiation and gene flow patterns that contribute to the understanding of cassava’s domestication history (Ogbonna et al., 2020). Figure 1 Representative species within the Cerrado radiation clade show high morphological diversity in spite of low phylogenetic differentiation (Photo credit: Simon et al., 2021) Image caption: Forms include the following: (a–d, h–j) subshrubs<30 cm tall growingannually from thick woody underground structures; (e–g, k) shrubs with slender stems up to 3 m tall; (d) unilobed leaves; (f) multilobed leaves withentire lobes; (c) pinnately lobed leaves; (c, d) short petiolate rosette-like leaves; (c, h) multilobed leaves with dissected lobes; (g) leaves withnaviculate lobes; and (a, e, f, j, k) peltate leaves; flowers arranged along an extended axis (b, i) above the foliage or (d, j) immersed within thefoliage. Most species within this clade are narrow endemics restricted to one or few localities within the Cerrado (Adopted from Simon et al., 2021)
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