- IITA’s Hartmann on the BBC.
- Bats protect coffee plants from insect pests.
- GBIF grants awards, pollinators well covered.
- New fungal disease threatens avocado production.
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.
Nibbles: Donkeys, UG99, fruit GI, negected species, Spore
- Cypriot wild donkeys in trouble.
- Gates Foundation tackles wheat rust UG99. Phew!
- Malaysians measure fruit glycemic indices, no mention of varieties.
- English exposed to neglected species.
- Sorry, missed the redesigned Spore.
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.
Yams in New Caledonia
Danny has just sent me this great old postcard from New Caledonia: “Preparations for a family celebration.” You can see how central yams are to Kanak culture. In 2004 the Kanak Traditional Senate established a Conservatoire de l’Igname. I never visited it, but I saw photos of it when a couple of the people responsible, including a senator, came to our regional plant genetic resources network meeting in Fiji a couple of years ago, and it looked great. Unfortunately, it doesn’t seem to have much of an online presence. Yet.
