After hanging out with experts for three days here in Cali, this is what I think I know about cassava genetic diversity:
- There’s a hotspot in Brazil, but Central America is pretty diverse too. Those two places are also where the wild species are most numerous. There is geneflow between wild and cultivated populations.
- There’s little geographic structure within the New World diversity, except for Guatemalan material being way genetically distinct (and higher in protein to boot). Lots of geneflow, I guess.
- The African material is less diverse than the American, but not much, and significantly distinct from it. Selection, and isolation.
- Within Africa, the Nigerian material is somewhat distinct. In general, there is more geographic structure in Africa than in the Americas.
- Asia received material historically from both Brazil (via Africa) and Mexico (via the Philippines), but there hasn’t been the differentiation there that is seen in Africa. There hasn’t been as much selection of natural hybrids in Asia as in Africa.
- Weird mutants keep turning up, including “sugary cassava,” “ketchup cassava” (the pinkiness is due to lycopene), and amylose-free clones.