Category: Wild relatives

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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.

ResearchBlogging.org 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:

  1. Households growing traditional varieties generally grow more than one (1.38-4.25).
  2. Households within a community tend to grow somewhat different sets of traditional varieties.
  3. 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.

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Momi-2008

The latest of Mitsuaki Tanabe’s monuments to wild rice was unveiled in the FAO building in Rome yesterday. Tanabe has donated this sculpture to the Global Crop Diversity Trust, and it is now installed by a window just in front of the Trust’s offices. Representing a seed of Oryza meridionalis, which is found in northern Australia, “Momi-2008” is about 9 m long and about 250 kg in weight. It took 20 men to get it up the stairs. This photo doesn’t really do it justice.

momi.JPG

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African protected areas surveyed

The EU-funded “Assessment of African Protected Areas” is out:

The purpose of the work is to provide to decision makers a regularly updated tool to assess the state of Africa PAs and to prioritize them according to biodiversity values and threats so as to support decision making and fund allocation processes.

It is great stuff: detailed, standardized descriptions of the importance of — and threats faced by — each protected area in Africa. I wonder if something similar will ever be done for agricultural biodiversity. An interesting first step might be to mash these results with those of the recent survey of crop wild relatives in protected areas. Unfortunately, the agrobiodiversity and protected areas communities hardly ever speak to each other.

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Imagining the past

And another trifecta to round off the day, this one of stories about the historical remains of agrobiodiversity, in a broad sense.

We start with an article in Britain’s Daily Telegraph about a genetic study of the skulls of a couple of lions from the menagerie which medieval royalty maintained in the Tower of London. It turns out they were Barbary lions from North Africa, now sadly extinct. Ok, they’re not strictly speaking agricultural biodiversity, but it’s a fun story and I couldn’t resist it.

Next there’s news of an excavation in Egypt which revealed the buried remain of donkeys. I think we actually nibbled this a few days ago in another guise, but the NY Times article is worth reading. The find is interesting because although the donkeys were definitely used as pack animals (the evidence is wear and tear on the bones), they didn’t look any different from wild asses — at least as far as their bones are concerned. Certainly they were no smaller, and a rapid reduction in size has been seen as a marker of animal domestication — the domestication syndrome. So, time for a rethink there.

And, finally, the Boston Globe has a piece on an exhibition of Jewish mosaics from Roman North Africa, entitled “Tree of Paradise” because of its depictions of nature’s bounty. Ancient representations of plants and animals are fascinating, because they are really the only way we can know the external phenotype of old, extinct breeds and varieties. There are unfortunately no pictures in the article, and the exhibition website only has one. Pity.