Category: Genetic erosion

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Can wild relatives survive introgression?

Crops can benefit from the introgression of genes from their wild relatives, but what about the other way around? Is the survival of crop wild relatives jeopardized by the “genetic pollution” caused by hybridization with the cultigen? A paper just out in the Journal of Applied Biology takes an experimental and modeling approach to answering this question ((D. A. P. Hooftman, M. J. De Jong, J. G. B. Oostermejer, H. C. M. Den Nijs. 2007. Modelling the long-term consequences of crop-wild relative hybridization: a case study using four generations of hybrids. Journal of Applied Ecology 44 (5), 1035–1045.)).

The researchers monitored the germination, survival and seed-set of hybrids between wild (Lactuca serriola) and cultivated lettuce (L. sativa). The overall fitness of hybrids was higher than that of the “unpolluted” wild relative in the first couple of generations, but as those hybrids were selfed and backcrossed, their fitness decreased. These data were then entered into a model, to see what would happen over time to a L. serriola population exposed to geneflow from the cultigen. What happens is that the wild relative can indeed be completely displaced by hybrids, but that is not a foregone conclusion, and in any case displacement, if it takes place, will not be as rapid as predicted by previous models which did not take into account the breakdown in heterosis.

So genetic pollution does pose a real threat to crop wild relatives in the field ((The likelihoods of both hybrid occurrence and L. serriola displacement were still at least 60%.)), but perhaps not as great as some have suggested. And in any case we now seem to have a model that can be used to assess the risk of genetic pollution, including by transgenes.

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Home is where you make it

Professor Roy Ellen, the project director, said: “This project aims to better understand the levels of agrobiodiversity found in home gardens – that is those gardens intimately linked to individual households. For example, we want to know where seed and other plant material comes from, whether it is purchased or obtained informally, who gives and receives it; who receives vegetable produce, and the economic scale of such exchanges. We wish to learn how people learn to become good home gardeners. Whilst biological diversity in itself is important, so are the skills and knowledge that maintain it.”

If you were a reasonably active member of this community and you read the above quotation you might just possibly think, “Ah. Another project to explore the value of agricultural biodiversity and the social networks that support it in some far-flung corner of the developing world. Nepal, maybe, or Burkina Faso.”

But you would be wrong. For the quote comes from an announcement of a project to study home gardens in that most English of settings, Kent. ((I’m giving it more space than Luigi’s original nibble, because I think it is worth it.)) This is exactly the sort of thing I think is sorely needed to forge links among people worldwide. I’ve not been able to find out that much more about the project, although it seems that at least some people at the University of Kent are admirably qualified. And both the Eden Project and the Royal Botanic Gardens, Kew, “will help with the dissemination of the project output”. I hope that means that they will draw the connections to home gardeners everywhere.

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Disappearing languages, disappearing agrobiodiversity

There are about 7,000 languages currently spoken around the world. By 2100, there will half that, if we’re lucky. That’s according to Harrison and Gregory Anderson of the Living Tongues Institute for Endangered Languages in Oregon, who “traveled the world to interview the last speakers of critically endangered languages as part of the National Geographic Society’s Enduring Voices Project.” Here’s a telling quote from Harrison Anderson:

Most of what we know about species and ecosystems is not written down anywhere, it’s only in people’s heads.

Just compare the map of hotspots of language loss with those of centres of crop origin and diversity. When the last native speakers of those 3,500 doomed languages go in the next century or so, they’ll be taking with them irreplaceable knowledge of agricultural biodiversity. Knowledge which we’ll need to make the most of that agrobiodiversity, and indeed to conserve it in situ (should we wish to) ((Or, indeed, should we be able to, given what climate change is going to do. Anyway, thanks to Ola for pointing out the article.)).