From Genes to Landscapes in Mesoamerica

From a special correspondent at the 6th Henry A. Wallace/CATIE Inter-American Scientific Conference on “Agrobiodiversity in Mesoamerica — From Genes to Landscapes.” Taking place 20-24 September 2010, at CATIE, Turrialba, Costa Rica.

Four days packed with presentations and discussions on Agrobiodiversity in Mesoamerica. And what biodiversity! Beans, maize, coffee, cacao, peppers … there is little to match the domestication feats of Central America! As part of the backdrop to the meeting, hosted by CATIE in Costa Rica, the gently fuming Volcano Turrialba is a quiet reminder of the turbulent rise and fall of civilisations and the dynamism and resilience of their culture.

The dynamism of agricultural systems was a striking recurrent theme of the first day’s talks; a morning dedicated to agricultural landscapes and an afternoon on the agricultural diversity in the landscapes. The symposium organiser, Fabrice DeClerck of CATIE, gave an inspiring introduction to the meeting, insisting that biodiversity is no longer a luxury item on the world’s development agenda. No-one needs to persuade policy makers anymore that biodiversity is central to the achievement of the Millennium Development Goals — a point made by Peter Kareiva and Michelle Marvier in Conservation for the People.

The issue is not so much the importance of biodiversity anymore, but how to pin it down … or at least how to focus on the important parts. Chili peppers are not spicy because we like them that way. Or not only. The heat-inducing biochemicals make the chili seeds resistant to attack from fungi while maintaining their attractive appeal to bird dispersers. Human’s domestication and use of chili peppers as a major ingredient in indigenous cuisine the world over, of course, is a happy sideline to what is clearly the result of very dynamic ecosystem processes. So which bits to save?

Jeremy Haggar of CATIE illustrated further the amazing dynamism of agricultural systems. In a study of tree species in coffee agroforestry systems he inventoried 16 smallholder farms in Nicaragua. Among the 110 tree species he identified, farmers selected a small number of species (5 or 6) that they wished to remove from their farms in favour of more useful species. Three years later, returning to the same farms, he was surprised to find that more than 30 of 110 species had disappeared, but that some 30 species were also new to the farms. Natural processes of colonisation had been considerably more effective at changing species composition than the farmers!

Jeremy also rang alarm bells, repeated by a number of speakers, about another looming source of dynamism, climate change. There will be a 60% reduction in the area suitable for coffee cultivation in Central America by 2050, as these cultural systems are driven uphill. Systems may be dynamic but it is not clear how ultimately resilient they are.

From the species perspective, Xavier Scheldeman of Bioversity International and Daniel Debouck of CIAT both described loss of populations of unique crop diversity: Capsicum flexuosum, a rare chili wild relative, has disappeared from the few collecting sites from which it was known in Paraguay as soybean cultivation has taken over. Similarly, one of the few populations of a wild bean species in Costa Rica has been built over. New populations of C. flexuosum have, fortunately, been found using targeted, GIS-aided collecting. The bean is also, thankfully, safely secured in the Svalbard Global Seed Vault.

So far, no connection has been made between crop species or relatives with priority traits for conservation and the ecosystems or landscapes in which they may be conserved. Clearly, a little more joined up thinking is needed. Bringing together this mixed bunch of scientists is a good start, and at the end of the four days the intention is to develop a white paper to guide policy-makers on priorities for agrobiodiversity conservation in Mesoamerica. Stay tuned!

Nibbles: Ireland, Plumpy’nut, Saola, Food heritage protection, Millet, Wild veggies, Brassica, UNMDGs, Ukraine

  • Celebrating the Irish Seed Savers Association celebrations. We had wanted to be there…
  • CAS-IP on how to “break” the Plumpy’nut patent.
  • Cattle wild relative seen for first time in 10 years. Well, by scientists anyway.
  • “Initiatives that merely codify cultural products without taking the social-organizational context into account risk becoming little more than ‘museums of production.'” Ouch.
  • Millet domestication pushed back in time.
  • Antioxidant properties of traditional wild Iberian leafy greens. Yes, I know, this medicalizes nutrition, but I thought it was interesting that these wild species are still used.
  • “…a trait of the diploid species, which apparently looks undesirable, might in fact be highly valuable for the improvement of amphidiploids…”
  • “Food? We don’t need no stinkin’ food,” say UN negotiators.
  • UK ambassador’s observations on agriculture in Ukraine. Love the contrast between 100 ha fields of sunflowers and the table groaning under home-grown fruit and vegetables.
  • In other news, the UK’s ambassador to Ukraine has a blog. And so do a number of others. Sorely tempted to subscribe to their RSS.

Nibbles: Dingo, In vitro, Human diseases, Aphandra natalia, Cave fish, Pets, Pavlovsk, Elderberry, Urban ag, Chilies

Nibbles: European plant conservation, Homegardens, Anthropogenic vegetation, Soil Association, Wheat and heat, Coconut meet, Pavlovsk beatdown, Plant species numbers, Vegetation and climate change, Genebank software

Getting the most out of wild tomatoes

ResearchBlogging.orgWhere should breeders look for traits like drought resistance among the landraces and wild relatives of crops? The FIGS crowd says: in dry places, of course. And they have a point. But it may not be as simple as that, as a recent paper on wild tomatoes shows. ((XIA, H., CAMUS-KULANDAIVELU, L., STEPHAN, W., TELLIER, A., & ZHANG, Z. (2010). Nucleotide diversity patterns of local adaptation at drought-related candidate genes in wild tomatoes Molecular Ecology DOI: 10.1111/j.1365-294X.2010.04762.x))

The authors looked at the diversity of two genes implicated in drought tolerance, nucleotide by nucleotide, in three populations of each of two closely related wild tomato species from the arid coastal areas of central Peru to northern Chile. Annual precipitation at the collecting sites ranged from 5 to 235 mm. As another recent paper put it, the tomato genepool “has both the requisite genetic tools and ecological diversity to address the genetics of drought responses, both for plant breeding and evolutionary perspectives.” Here’s where the populations came from: 1-3 are Solanum peruvianum, 4-6 are S. chilense.

These places are pretty dry. Here’s what a close-up of the driest (number 3) looks like:

Anyway, Hui Xia et al. found evidence of purifying or stabilizing selection at one gene, called LeNCED1. So far so good. But they also found a pattern of variation at the other gene, pLC30-15, in one of the populations (number 4, S. chilense from Quicacha in southern Peru) which they interpreted as evidence of diversifying selection, where “two alleles compete against each other in the fixation process.”

Now, that would arguably be a more interesting population for a breeder to investigate than any of the others, but the observation “is difficult to explain based on the environmental variables of the populations investigated.” Ouch, say the FIGS crowd! ((Actually, it’s not as bad as that, that other paper I quoted earlier has this to say: “We confirmed that several eco-physiological traits show significant trait-climate associations among climate-differentiated populations of S. pimpinellifolium, including strong association between native precipitation and whole-plant tolerance to water stress.”)) But is it perhaps that the authors just considered average rainfall, and not how variable rainfall was at the site, from year to year? The best they can suggest by way of explanation is that S. chilense is an endemic with a very narrow ecological amplitude. In contrast, S. peruvianum is more of a generalist, with larger, expanding populations, found in both dry and mesic locations: “this may not be favourable for the occurrence of adaptive evolution, either because phenotypic plasticity can be promoted rather than local adaptation or because beneficial mutations are more likely recruited from the higher genetic standing variation.”

So, target dry areas for adaptation to drought tolerance, by all means, but the environment is not all, and some wild species may be more useful than others in providing interesting diversity depending on their ecological strategies and population dynamics.