Category: Genetic diversity

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An early look at an atlas of agrobiodiversity

On reading about the Atlas of Global Conservation here a few days ago, Nora Castaneda of Bioversity International’s Regional Office for the Americas sent me some of her own forays in that area, which are focused on plant species of agricultural interest. They’re still works in progress, and unpublished, ((Which is why I’m only putting up pretty low resolution images.)) but definitely worth having a quick look at. The data comes from germplasm databases (SINGER, GRIN, EURISCO) and the databases put together for the GapAnalysis project, about which we have already blogged about here.

Here’s what the distribution of numbers of accessions of varieties of the major food crops in genebanks looks like. Dark brown means lots of different accessions (not varieties, mind!).

One has to wonder what’s going on in Spain. As I say, it’s a work in progress. A certain amount of data cleaning may still be necessary, for example to identify duplicates and take them out of the equation. And when Genebank Database Hell allows it should even be possible to take into account morphological and genetic diversity.

Anyway, here’s the distribution of richness of wild relative and landrace accessions of a number of major crops. Green means lots of species and landraces.

When finished, I think these maps will make a great complement to the Nature Conservancy’s Atlas. But would the biodiversity community be interested?

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Research on Ethiopian food insecurity not very joined up?

The Drylands Coordination Group (DCG) is a network for capacity building through exchange of practical experience and appropriate knowledge on food security in the drylands of Africa.

And a huge amount of very detailed research they are doing too, in Mali, Eritrea, Sudan and Ethiopia. But one does have to wonder how much “exchange of practical experience” is really taking place. Take two reasonably recent reports from Ethiopia.

One, entitled “The Levels, Determinants and Coping Mechanisms of Food Insecure Households in Southern Ethiopia” (published Feb. 2009) makes no mention of diversity within crops at all. In fact, it even conflates crops, by measuring household economic status as the “average amount of wheat per person (all household production converted into wheat term).” Surely it makes a difference to the “levels, determinants and coping mechanisms of food insecure households” whether they are producing only one variety of wheat, several varieties of wheat, or both wheat and other cereals.

Compare that with another DCG study, entitled “Seed system impact on farmers’ income and crop biodiversity in the drylands of southern Tigray” (published Jan. 2009). This goes into great detail on the different varieties of each of the cereal crops in the study area.

Surely the two teams could have talked?

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Restoration is germplasm use too

ResearchBlogging.orgIt is well known that plant populations do best when they grow close to where they originally came from. A myriad reciprocal transplant experiments going back decades attests to the power of local adaptation. But how close is close? The question is of very real practical importance if you’re trying to restore a habitat. By definition, the local population is gone. What is the maximum distance you should be willing to go to collect material to re-establish it?

Three hundred kilometers is the answer given in a paper just out in Ecological Applications. ((Travis, S., & Grace, J. (2010). Predicting performance for ecological restoration: a case study using Spartina alterniflora Ecological Applications, 20 (1), 192-204 DOI: 10.1890/08-1443.1)) There’s also a discussion over at Conservation Maven. The authors worked on the salt marsh grass Spartina alterniflora, which is commonly used in ecological restoration of wetlands in North America. They collected germplasm at 23 sites from Texas to Maine, genotyped them using neutral markers, and then grew them all in a “common garden” experiment in Louisiana, where they measured in various ways how well each population did. The control was a population just across a canal from the experimental site.

It turned out that clone diameter, number of stems and number of inflorescences at the experimental site, as well as genetic distance, were all significantly affected by measures of the geographic distance between the source and the experimental site. For populations up to about 300km away along the coast, performance in the common garden was similar to the control. Go further, and the source populations do not do as well where they are planted.

The authors make quite specific recommendations for restoration. Use material from at least three populations within 300km of the restoration site, and 100km if you want material that is not only maximally locally adapted but also not significantly genetically different from the original population at the restoration site.

Now, I don’t know how widely applicable these recommendations might be. I don’t know the restoration literature at all. A cursory look revealed a fairly well-developed theoretical framework, the “restoration gene pool concept.” Which has been used to develop a decision support tool.

As I say, I don’t know much about restoration. So I don’t know to what extent this sort of thing has been applied to crop wild relatives. To me, “use” of crop wild relative germplasm means use in breeding. But that is clearly very narrow thinking, and I should be ashamed of myself.

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Measuring diversity in Tibetan walnuts

You collect leaves from 220 walnut trees of two morphologically very distinct species (Juglans regia and J. sigillata) from two unrelated groups of families of villagers in each of six different villages in Tibet. You get the gene-jockeys to do their microsatellite stuff on the leaves. You calculate the contribution of species, of the kin relationship of the growers and of village to genetic diversity. You expect the biggest genetic differences to be between species.

You are wrong.

Yes, the “species,” which look totally different, are in fact indistinguishable genetically. But there were significant differences among villages, and smaller but still significant differences between unrelated families of farmers within villages. So, you might be particularly interested in certain traits, for improvement say (and so are the farmers: walnut landraces in this part of Tibet are often named after fruit phenotypes). But — in this case — morphology is not a great guide to the totality of the underlying genetic diversity. So you can’t use it alone for conservation.

Which is also the conclusion researchers in Benin arrived at in their study of another tree, akee (Blighia sapida), also just out. A conservation and use (domestication, in this case) strategy “should target not only the morphotypes recognized by local populations but should also integrate the population genetics information.”

Does this amount to a general rule?