Category: Domestication

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Cassava diversity 101

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. 
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Avocado domestication and iconography

I took advantage of the thirteen hour flight to Lima to catch up on some reading, including a recent paper reviewing the state of knowledge on avocado diversity and domestication. ((Mari­a Elena Galindo-Tovar, Nisao Ogata-Aguilar and Amaury M. Arzate-Fernandez (2008) Some aspects of avocado (Persea americana Mill.) diversity and domestication in Mesoamerica. Genetic Resources and Crop Evolution 55:441-450. http://dx.doi.org/10.1007/s10722-007-9250-5.)) The authors postulate that avocado exploitation began in Central Mexico with the gathering of fruits from the forest, possibly as long ago as 8000 BC. Then, when the climate changed for the worse around 4500-2000 BC, people began to tend and cultivate the tree in forest gardens. The final phase was one of intensive cultivation in homegardens and active dispersal around the region and into South America.

That’s all very interesting, but the thing that really stuck with me was the observation that the avocado tree is represented on Hanab-Pahal’s sarcophagus from Palenque. Not on the famous “astronaut” lid, however, but on its side. Ten ancestors are seen around the sides of the sarcophagus, arising from a crack in the earth, each with a fruit tree, forming a sort of homegarden around the dead king. Among them is Lady Olnal, and she has an avocado tree. Unfortunately, I couldn’t find a picture of this on the internet. But the reason it struck me is that I’d just been looking at photos of more recent, and geographically somewhat distant, but no less botanical, funerary art. Even in death, people of all ages and cultures like to be surrounded by plants, it seems.

And, being in Peru, all this rumination about art and agrobiodiversity couldn’t help but remind me of Marcos Zapata’s painting of the Last Supper in Cuzco Cathedral (1753). That famously features roast cuy, but check out the thing to the left of the cuy’s head. Is it a maca? What other crops can you identify? Donwload the full-sized version on the photo and see. No avocados, alas.

cuy.jpg

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Bye bye, Miss American (Apple) Pie?

Maybe it was the discussion about apple varieties during the 60 Minutes piece on Svalbard:

…in the 1800s in the United States people were growing 7,100 named varieties of apples. 7,100 different varieties of apples that are catalogued,” Fowler explains.

“And how many are there today?” Pelley asks.

“We’ve lost about 6,800 of those, so the extinction rate for apples varieties in the United States is about 86 percent,” he explains. 

More likely it was just the general interest in genebanks and crop diversity generated by the Svalbard phenomenon. In any case, it is great to see a mainstream publication like The Alantic Monthly waxing lyrical about apple conservation. Via The Fruit Blog.