- Social networking for livestock. Not as silly as it sounds.
- Fish in the Tea. Dr Seuss unavailable for comment. Via.
- Natura 2000 network expands. Good for wild relatives? Does anybody know? Care?
- Brits flocking back to their allotments? I spot an opportunity for seed savers and heirloom varieties.
More on meta-analyzing diversity
You may remember a post a few days ago summarizing something of a milestone paper by Bioversity scientists and partners which analyzed ten years’ worth of data on the diversity of 27 crops on farms in 8 countries around the world. As you’ll see if you revisit the original post, there’s been interesting discussion of the paper in the comments section. But I’ve been engaging the writers by email as well and it might be worth recounting the gist of that conversation.
The main point, I guess, is that they consider the crux of the paper as not so much the discussion of how/why diversity is being maintained on farm, as the fact that the richness/evenness relationship makes it possible to estimate one from the other (though separately for different kinds of crops). They see this as establishing really quite a novel framework for discussing — and generating hypotheses about — crop diversity.
It seems to me the discussion has started already.
Ugandan discussions about Ankole
Jeremy has already blogged about these articles, but I didn’t get around to reading them until this past weekend, and a connection between them struck me, so forgive me for linking to them again. They’re both worth reading again anyway.
The first is a piece in Wilson Quarterly entitled The Coming Revolution in Africa. It purports to be optimistic about the future of African agriculture, but in fact it ends up being a bit of a downer, even if you accept its premise. Part of that premise is that agricultural experts have got it wrong in the past, which seems fair enough, but is it really the case that
Disdainful of the market, these agricultural specialists preferred to obsess over arcane questions about soil quality, seed varieties, and some mythical ideal of crop diversity. In classic Âbutt-Âcovering mode, they blamed “market failures†and Africa’s geography for farmer’s low incomes and their vulnerability to famine and food Âshortages.
“Some mythical ideal of crop diversity”? What is that supposed to mean? But the quote that really struck me was this one:
Then he criticizes the country’s traditional Âbig-Âhorned Ankole cattle. These animals are beautiful and beloved but provide very little milk, he says, “no matter how hard you squeeze.†He prefers European Friesian cows. “Five of them will produce the same as 50 Ankoles,†he Âsays.
The person speaking is Gilbert Bukenya, vice president of Uganda. The comment jumped out at me because I had previously been reading about the views of his boss on the same topic:
President Yoweri Museveni once imposed a ban on imported semen. Museveni belongs to the Bahima ethnic group. When he was a baby, in a sort of Bahima baptism ritual, his parents placed him on the back of an Ankole cow with a mock bow and arrow, as if to commit him symbolically to the defense of the family’s herd. Museveni, now in his 60s, still owns the descendants of that very cow, and he retains a strong bond to the Ankole breed. Two years ago, I accompanied a group of Ugandan journalists on a daylong trip to one of the president’s private ranches, where he proudly showed us his 4,000-strong herd of Ankole cattle. At one point, a reporter asked if the ranch had any Holsteins. “No, those are pollution,†Museveni replied. “These,†he said, referring to his Ankoles, “the genetic material is superior.â€
This latter quote comes from a long, careful piece in the New York Times about the future of the Ankole cattle.
There must be some very interesting cabinet meetings in Kampala.
Evidence-based conservation
The latest issue of the Cambridge Alumni Magazine has a section on biodiversity conservation. Nothing at all on agrobiodiversity, alas, but a footnote did send me to an interesting video of Prof. William Sutherland talking about “evidence-based conservation.” ((Prof. Sutherland was also behind the article horizon-scanning biodiversity threats which we nibbled a few days back.)) He also says nothing specifically about the importance of conserving agricultural biodiversity — which is ironic given that the opening example in his talk concerns the nutritional importance of the fruit of a cultivated species — but I think his thesis is generally applicable. And that thesis is, paraphrasing somewhat, that there are too many meta-narratives in conservation and not enough data. ((Ok, that is itself a meta-narrative. Or a meta-meta-narrative? My head hurts.)) He’s put together a website where experimental evidence for and against the efficacy of specific interventions aimed at solving specific conservation problems can be documented and discussed.
Meta-analyzing diversity
If you’ve just arrived from Tangled Bank, welcome. And be aware that there’s a follow-up post.
A couple of meta-analyses on the menu today.
Devra Jarvis and Bioversity International colleagues, together with numerous co-authors from national programmes around the world, have a paper in PNAS summarizing the results of a 10-year effort to establish the scientific bases of on-farm conservation of agrobiodiversity. ((Jarvis, D.I., Brown, A.H., Cuong, P.H., Collado-Panduro, L., Latournerie-Moreno, L., Gyawali, S., Tanto, T., Sawadogo, M., Mar, I., Sadiki, M., Hue, N.T., Arias-Reyes, L., Balma, D., Bajracharya, J., Castillo, F., Rijal, D., Belqadi, L., Rana, R., Saidi, S., Ouedraogo, J., Zangre, R., Rhrib, K., Chavez, J.L., Schoen, D., Sthapit, B., Santis, P.D., Fadda, C., Hodgkin, T. (2008). A global perspective of the richness and evenness of traditional crop-variety diversity maintained by farming communities. Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0800607105))
Varietal diversity ((The unit of analysis was the farmer-recognized and named variety.)) data on 27 crops grown on 64,000 ha by 2,041 households in 26 communities in 8 countries on 5 continents were pulled together in a stunning feat of synthesis. Are any generalizations possible from such a massive dataset? Well, perhaps surprisingly, yes. Let me pick out the highlights:
- Households growing traditional varieties generally grow more than one (1.38-4.25).
- Households within a community tend to grow somewhat different sets of traditional varieties.
- Larger fields generally have more traditional varieties, but smaller fields tend to be more different in varietal composition.
There’s much more to this rich analysis than that, but the take-home message can be pretty easily stated: crop genetic diversity can still be found on-farm because even neighbouring families choose to grow different traditional varieties, and generally more than one. Especially families tending smaller fields, who will presumably be poorer and living in more marginal conditions. The conoscenti will recognize a familiar meta-narrative, but it is good to have solid data from a wide range of crops and from all over the world.
The next paper I want to talk about looked at genetic diversity in wild clonal species as it relates to their breeding system. ((Honnay, O., Jacquemyn, H. (2008). A meta-analysis of the relation between mating system, growth form and genotypic diversity in clonal plant species. Evolutionary Ecology, 22(3), 299-312. DOI: 10.1007/s10682-007-9202-8))
Summarizing 72 genetic diversity studies, including of a couple of crop relatives, the authors found that populations of self-incompatible clonal species tended to have fewer genotypes, more unequally distributed (i.e., with a few dominant clones), than populations of self-compatible clonal species. It would be interesting to see if this relationship is also present in vegetatively propagated crops. I don’t think the previous dataset would help with that, however. Only two clonal crops were included in the on-farm analysis, cassava and taro. Interestingly, they had the highest average levels of community-level varietal richness (33) compared to seed-propagated species.