The latest issue of Oekologie, a blog carnival, is up at Laelaps. ((And thanks, Brian, for accepting a late entry.)) Some choice gems there in our line of work. 21st Century Citizen has a list of “six classic books on organic growing” that is (seeks delicate word) idiosyncratic. There are a couple in there that I would definitely agree with. A couple that I personally would ditch in favour of others. And a couple that I haven’t read. But hey! It’s her list. Maybe some day I’ll do my own. Then there’s a good post from Living the Scientific Life about a research paper suggesting that African farmers use African bees to manage African elephants. The idea is full of holes, as the authors ((One of them an old colleague. Hey Fritz, how’s things?)) are the first to admit, but nevertheless an interesting approach to a difficult problem.
Climate change will cause more than extinction
A comment in Conservation Biology this month ((D.K. Skelly et al. (2007) Evolutionary Responses to Climate Change. Conservation Biology 21 (5), 1353–1355. doi:10.1111/j.1523-1739.2007.00764.x)) criticizes a recent paper in the same journal ((J.R. Malcolm (2006) Global Warming and Extinctions of Endemic Species from Biodiversity Hotspots. Conservation Biology 20 (2), 538–548. doi:10.1111/j.1523-1739.2006.00364.x)) which estimated that up to 43% of the endemic biota in some biodiversity hotspots could go extinct as a result of global climate change.
While not disputing that climate change will cause extinctions, the authors of the comment suggest that the climate envelope approach to predicting range changes ((That’s the same kind of approach that’s been used by our friend Andy Jarvis and others to predict dire consequences for the wild relatives of the peanut, potato and cowpea.)) ignores the possibility that species may in fact evolve in response to changes in the climate. And they quote evidence that such genetic change is happening.
Continue reading “Climate change will cause more than extinction”
A history of viruses
We’re fond of reminding ourselves here that agrobiodiversity isn’t just crops and livestock and their wild relatives — it’s also pests and pathogens and weeds and pollinators and earthworms and brewer’s yeast. It’s one of our leitmotifs. Another is that agricultural and “wild” biodiversity interact. Here’s a paper that kind of brings these two leitmotifs together, into a sort of counterpoint, if I may be allowed to push the metaphor ((C.M. Malmstrom et al. (2007) Barley yellow dwarf viruses (BYDVs) preserved in herbarium specimens illuminate historical disease ecology of invasive and native grasses. Journal of Ecology (OnlineEarly Articles). doi:10.1111/j.1365-2745.2007.01307.x)).
Carolyn Malmstrom and her team at Michigan State University isolated RNA of barley and cereal yellow dwarf viruses from old herbarium specimens of Californian grasses, dating back to 1917. They used such historical samples to trace the history of these agriculturally important viruses back through time, building up a sort of family tree. The analysis suggests that the viruses were present in the Californian native flora in the 18th and 19th centuries, when invasive Eurasian annual grasses (some of them weedy crop relatives) displaced native perennial grasses. In fact, they may have facilitated this invasion by helping the exotic grasses outcompete the natives ((“Non-native invaders amplify spring aphid populations and increase BYDV infection in natives, which in turn suffer substantially reduced survivorship when infected.”)).
The team also found “potential correspondence in the timing of virus diversification events and the beginning of extensive human exchange between the Old and New Worlds.” Humans may have caused the branching of the family tree of some viruses by moving them and their hosts around the world.
Here’s Malmstrom on the significance of her work:
This work points out that the virus world does have an active, long-term role in nature, not just in agriculture… We very much need to understand how viruses can move and influence our crops. If we care about our crops, we need to care about what’s happening in nature.
So: aphids, viruses, native grasses, exotic weedy invaders, crops. Quite a fugue.
Seeds are not enough
An article in the NY Times tells a frustrating tale of agrobiodiversity use: stunning use by researchers, followed by disappointing use by farmers. It’s the story of Nerica ((The piece has been picked up elsewhere. The Economist’s Free Exchange blog also comments on it.)) — New Rice for Africa. This is a family of varieties derived in the 90s from a biotechnological breakthrough, the hybridization of African and Asian rice. ((Don’t get me wrong, these are not transgenics, though molecular methods were used to overcome the huge challenge of interspecific hybridization.)) Combining “the toughness of O. glaberrima with the productivity of O. sativa,” Nerica varieties have:
– Higher yields (by 50% without fertilizer, and 200% with).
– Earlier maturity (by 30-50 days).
– Resistance to local stresses.
– Higher protein content (by 2%).
A great example of researchers really unleashing the potential of genetic diversity. And one that has been rightly widely recognized. So why have the resulting varieties “spread to only a tiny fraction of the land in West Africa where they could help millions of farming families escape poverty”? It hasn’t been for want of trying:
To quickly move the NERICA technology into farmers’ hands, WARDA and its partners have adopted farmer-participatory approaches, such as the Participatory Varietal Selection (PVS) and community-based seed production systems (CBSS).
The NY Times piece suggests that the reason for Nerica’s disappointing use by farmers comes down to infrastructure. The seeds — even information about them — are not getting to the farmers that need them, and the harvest finds it hard to get to market. That’s because there are few seed companies, roads are bad, telecommunications poor, credit not available. The article also suggests that yield of Nerica has been known to decrease over time “because the new seed was not pure.”
It is undeniable that seed systems could be strengthened in Africa, and that doing so would improve the lot of smallholders. But I don’t know. Farmers are not stupid. They know how to select material for next year’s sowing, and they exchange seeds all the time, often over large distances. Their lives depend on it. Is there something else holding Nerica back? Or maybe it’s just too soon to be expecting miracles of adoption?
Time flies when you’re having fun
Has it really been a year? I suppose it has. Anyway, I’ve taken the opportunity to do a little housekeeping, upgrading to a new version of WordPress. Problem is, the real job calls and there are a couple of things I still need to sort out, like instructions for subscribing and getting rid of that goofy popularity rating thing.
We’re not going to overdo the celebrations here, but you could take the opportunity to sling us a few comments. What do you like? What do you hate? What would you like us to do that we don’t?
Flickr photograph by princessrica.