Category: Domestication

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Diversity in rice varieties: what caused it?

Larry Moran has a very good article on the genetic diversity found in the DNA of rice varieties. I won’t try to summarize what he has to say, because he says it so well. But I will emphasize something that he doesn’t. The biologists who looked at rice wanted to know what caused the pattern of diversity they see across rice vareties. One possibility is selection. The other is the founder effect, where a very small subset of a larger population gives rise to a new species (or variety) so that the new species contains less diversity than the ancestor population from which it sprang. In rice, neither explanation on its own is sufficient.

An agricultural scientist might not care one bit, or might simply assume that it was all due to selection by farmers. But the truth is that it needed a combination of the founder effect and positive selection to create modern rice diversity. The founder effect relates to the fact that Oryza sativa indica and Oryza sativa japonica were both domesticated independently from the wild Oryza rufipogon, maybe a few times. The results of those early events set up the foundation genes for rice. Then selection was brought to bear and created the diversity we now see. Luck and hard work, every time.

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Farming butterflies conserves forests

East African farmers are making good money — and conserving their local surroundings — by going after butterflies. The Manila Times picks up a story from Agence France Presse reporting from the villages in Kenya and Tanzania where locals have learned how to trade in butterflies. The article is built on the words of the farmers themselves, and it makes for uplifting reading. A sample:

“I would be foolish to cut trees,” says Suleiman Kachuma, a 42-year-old villager, who earns between 15 and 23 dollars a month from his work with Kipepeo, double what he used to make selling timber.
“Before, people had a few chickens and goats… Now there is a big change. Farmers have more chickens, some even have some cattle. The project really changed our lives,” he says.

I thought I’d seen this somewhere before, and I had.

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Tree domestication a huge success

There’s a heart-warming tale over at the Rural Poverty Portal (nice site, too) of the International Fund for Agricultural Development. A tree domestication project in west Africa has brought higher incomes and improved status for women, which has translated into schooling and better nutrition. Women are running their own tree nurseries, selecting which species to grow and nurturing them for market. So far the number of species is limited, perhaps that will improve. The project was implemented by the World Agroforestry Centre.

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Rescuing the American chestnut

You know, these Nibbles (the short, soundbite-type things which appear at the top of the right sidebar of this page) are fun to do, but sometimes you end up downplaying, or over-simplifying, an important, interesting — and interestingly complex — story. Take what I said about the American chestnut a few days ago. The recent history of Castanea dentata is proud and tragic ((Looking further back, it also played an important role in native America agroforestry.)), and efforts to bring it back from the brink of annihilation well-nigh heroic. To imply, as I did, that these efforts were confined to hybridizing the American with the Chinese chestnut was justified only by the necessity for extreme brevity. In fact, of course, it is not just hybridization but repeated back-crossing. And not just interspecific crossing but also painstaking crossing among the few remaining pure American chestnuts, as reported in the article that prompted me to revisit the original story and hopefully make amends for my earlier flippancy.