Author: Luigi Guarino

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Terrible news from the northern Pacific

My friend and colleague Lois Englberger has just written to say that the building which housed the Secretariat of the Pacific Community office in Pohnpei and the headquarters of the Island Food Community of Pohnpei burned down during the early morning of 4 April. Losses were great, though thankfully nobody was hurt. Both SPC and IFCP are active promoters of traditional foods, and have done great work documenting and conserving traditional varieties of Pacific crops, and not just in Pohnpei. What’s happened is a terrible blow, but I’m sure both organizations will make a full and rapid recovery and continue their vital work. My thoughts and best wishes are with Lois, Konrad, Adelino and all my other friends affected by this in Pohnpei and around the Pacific.

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What is the value of pollinators?

Exactly a year ago yesterday Jeremy wrote a post about the dollar value of pollination as an ecosystem service. Now comes an article in Gaia which argues that previous criticism of such valuations in the same journal are unfounded. ((Alexandra-Maria Klein, Roland Olschewski and Claire Kremen. 2008. The Ecosystem Service Controversy: Is There Sufficient Evidence for a “Pollination Paradox”? GAIA 17/1:12–16.)) A year is a long time in science.

The criticism in question was based on the observation that “crops depend on pollinators but crop yield does not necessarily depend on pollinators as other factors are likely to limit crop production.” Jaboury Ghazoul called this the “pollination paradox” ((Ghazoul, J. 2007. Recognising the complexities of ecosystem management and the ecosystem service concept. GAIA 16/3: 215–221.)) in an article which argued that it is impossible to value ecosystem services individually.

The authors of the latest paper dissect the situation with coffee and almond and conclude that “there is currently no evidence for a pollination paradox.” However, they do say that recent figures for the monetary value of pollination may well be media-driven overestimates. Even the often-seen figure that “one third of the caloric value of our food is derived from animal pollination … is still not well supported.” That pollinators are important to food production is not contested. But how important is perhaps not as easy to calculate as has been made out.

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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.