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.
Classifying conservation actions
An article in PLoS Biology recently suggested that IUCN should change the classification system it uses for protected areas (PAs). ((Change the IUCN Protected Area Categories to Reflect Biodiversity Outcomes Boitani L, Cowling RM, Dublin HT, Mace GM, Parrish J, et al. PLoS Biology Vol. 6, No. 3, e66 doi:10.1371/journal.pbio.0060066.)) Currently reflecting management intent (e.g. “National Park: managed mainly for ecosystem protection and recreation”), the idea would be for the new categories to rather “be based on the quality and quantity of the contribution of each PA to conservation of biodiversity (and associated sociocultural values).” So: actual result, rather than intent; and “what ” and “how much” rather than “how.” Seems like a pretty good idea. And it also seems like the concept could be applied not just to protected areas, but to conservation actions in general. That would spell the doom of the tired old in situ/ex situ dichotomy. Not a minute too soon, as far as I’m concerned.
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.
Nibbles: Anti-diversification, chickens, bananas, registers, tropical fruits
- US subsidy system prevents diversification. Via.
- Chicken domestication; possibly more than you could ever want to know.
- Red bananas; Raul unavailable for comment.
- Filipino community registers agrobiodiversity.
- Tropical fruit diversity conserved, studied and consumed in the US. That includes the citron. ((Note to Jeremy: that would be Citrus medica.))