A modest proposal

That last but one post of Jeremy’s got me thinking. How do we find out if Arachis ipaensis is still at that locality? I mean, short of mounting a fully-fledged expedition of groundnut experts at vast expense, that is. One way might be to ask a local person to check for us. Ok, a wild peanut species might not be the best thing to try this with, but you get the idea. Problem is, how do we identify a local person who knows that area?

Then I remembered something Jeremy sent me recently. WikiLoc is a website to which you can upload your favourite walk or cycle ride as a GPS track. You can then view all these in a number of different ways, including in Google Earth. So I gbiffed (sensu Cherfas, 2008) the localities of wild Arachis species and viewed them in Google Earth together with all the tracks from South America available on WikiLoc.

Well, of course, none of the trails was anywhere near the locality of A. ipaensis. But I did find others that came near — or very near — the localities of other species. Check this one out, for example:

It’s a 32 km circuit around Piribebuy in Paraguay, and it was uploaded by someone called Yagua. It takes about 4 hours to walk it. And it so happens that a specimen of Arachis glabrata was collected along Yagua’s favourite trail, around its southeastern corner:


Now, I don’t think A. glabrata is a particularly significant component of the groundnut genepool, but say, for the sake of argument, that it had been. Couldn’t we ask Yagua to keep an eye on it for us? Multiply by the more than 10,000 tracks on WikiLoc and pretty soon you’re talking about a real global network of agrobiodiversity monitors. But maybe we should test the idea out with a somewhat more — ahem — charismatic plant. And imagine if germplasm collectors start adding their tracks to WikiLoc.

Hot cocoa

fairtrade.jpgThe Fairtrade Foundation licenses this special mark to distinguish products that have been certified as meeting certain producer and trading standards, meant to ensure that small-scale producers and plantation workers in the developing world get a better deal. The producers “receive a minimum price that covers the cost of sustainable production and an extra premium that is invested in social or economic development projects.” And farmers are thus given an incentive to maintain agrobiodiversity on farm. However, as an article in last week’s Economist points out, this model is not particularly popular among the large corporations that control the global trade in agricultural commodities: “Fairtrade’s price-adjustment mechanism is intended to insulate small producers from volatile commodity markets and the free-trading, no-holds-barred capitalism that multinational companies espouse.”

And yet, Fairtrade-like strategies — The Economist calls them “Fairtrade lite” — are increasingly popular: “firms are finding ways to improve the lot of small farmers, and burnish their own reputations, without signing up to Fairtrade’s rules.” The article describes the latest example.

It is called the “Cadbury Cocoa Partership,” and it commits that multinational to investing US$87 million over 10 years in increasing cacao yields in Ghana. That country provides Cadbury Shweppes with 70% of its global needs (100% of its UK needs), amounting to 10% of Ghana’s production. A recent study showed that yields have been decreasing and youngsters leaving the farms, imperilling supply. Cadbury does use a Fairtrade-certified cocoa (from Belize), but in this case it decided that the problem was not so much price as productivity, and came up with its own scheme.

Intercropping will be encouraged (peppers, mangoes, coconuts) as an additional income option, wells dug to free up the time of women and girls, and schools and libraries built, equipped and staffed. But it is unclear how productivity is to be increased. The article says that “the aim of the venture is to show cocoa farmers how to increase yields using fertilisers and by working with each other.” Surely that’s not going to be enough. Hopefully cacao genetic resources conservation, evaluation and breeding work will also be supported.

More to maize evolution than selection

Our thanks to Hannes Dempewolf for this guest post.

ResearchBlogging.org What forces drive maize evolution and what factors contribute to the generation of maize agrobiodiversity? This question has been the focus of a recent study, published in PNAS.

Contrary to the popular opinion that maize diversity at present is largely a result of artificial selection on local germplasm, the authors call for careful consideration of the ‘larger social context of maize evolution’ and explore the implications of ‘farmer-led selection’ on maize diversity. Using a theoretical approach, underpinned with some empirical data, they investigate the interplay between farmer-led selection and informal seed systems. This can result in the spread of varieties that are not necessarily ones of superior agronomic properties, but are favoured due to other factors, such as superior seed supply mechanisms:

…A frequent supplier of seed might be a farmer whose seed is faithful to a type. His seed line will be well represented locally or even fixed… Another farmer that keeps a stock of maize might be known as a sure supplier of seed when others are lacking. His seed might not be preferable to others’ but might still become locally predominant if the seed population is small. If the population is large, the demographic outcome depends not only on the rate at which he gives out seed but also on how long he keeps it.

In the context of their discussion of seed replacement, they correctly recognize that

High revenue is of less concern to subsistence farmers, who deal with a larger set of issues and overwhelmingly prefer landraces…New seed does not always perform well, especially nonlocal types acquired through informal seed systems. Farmers test seed and discard ill-adapted and inferior types. Most introduced seed is replaced after its first year, more than twice the rate of local seed.

However, introduced germplasm which has not been discarded might introgress into local seed stocks and help to maintain diversity: “When more variation within a locality is lost than created, an external source is required to maintain diversity… It is unlikely that introduced seed is displacing local types systematically.” This is because most introduced seed is not kept true to type but hybridizes with local landraces. What the prevalence of hybridization means for the genetic makeup of local landrace varieties is still unclear, but this question has received considerable attention lately, especially in the context of GMO risk assessments.

The view that, once markets are well developed, farmers shift to adopting improved varieties and hence cease to maintain diversity seems not to hold true in the case of maize in Mexico. There doesn’t seem a loss of diversity even in well developed markets. Diversity at the local level might instead be the result of individual farmer’s unintended actions, as described above.

Further contemplating the role of farmers in maize evolution, the authors suggest:

Farmers’ main goal is appropriating value, whether economic, cultural, or ritual. Whereas some might achieve this through improvement of local seed stocks, others might prefer to keep these stocks unchanged, defying our conceptions of improvement. Others may find it optimal to replace those stocks. It does not follow that seed improvement and conservation traditionally have been performed by farmers specialized as seed curators. Unlike modern maize farmers and breeders who specialize in distinct tasks, most Mexican farmers engage in seed improvement, diffusion, and farming simultaneously. Although individual management decisions have a specific intent (i.e., to preserve or replace seed), it is the sum of farmers’ actions that drives changes in maize populations. These actions can have unintentional albeit predictable effects on the metapopulation dynamics of maize.

One limitation of their study, as the authors acknowledge, is their assessment of the system at one single point in time. They suggest that even after major disruptions of the seed systems, such as catastrophic weather events, normal dynamics are bound to return after seed diffusion through government and relief agencies has ceased. Although these dynamics might indeed return, it would be interesting to see how the genetic makeup of the maize genepool changes in response to human intervention on such dramatic scales.

Social aspects of crop evolution, although undeniably of great importance, have received only limited attention by many students of evolutionary theory. One can only hope that papers like this spark the debate and contribute to a more rigorous scientific exploration of these complex interactions between social factors and crop population genetics.

It should be interesting to see how demographic modelling attempts on the evolution of crops other than maize are taking into account these factors. One could well imagine that this might lead to a major change in the way crop evolution is understood by many researchers.

A maize tour

SIRGEALC over, Marleni, David and I headed for CIMMYT, the International Maize and Wheat Improvement Centre. That’s in Texcoco, about an hour’s drive from the hotel where we were staying in Mexico City (or three hours, unfortunately, on the way back). It turned out to be something of a maize odyssey. I’ll tell the story in pictures.

When we got to Texcoco, it was too early for lunch, but that didn’t stop us spending some time in the market sampling the local cuisine, as the quesadillas there are famous. This lady certainly made us some great ones. Note the two types of maize she’s using.


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