- Eating frog legs is bad. France surrenders.
- Oxford boffins to map world’s sacred forests.
- Lafort onion: from the Wellesbourne genebank to Irish Seed Savers to urban kitchen garden.
- Lobster 101.
- A wild relative in trouble any way you slice it.
- And one that gets around. Didn’t we blog about this before? Yep.
The pros and cons of genetic pollution
Is genetic pollution necessarily a bad thing? Well of course there’s pollution and pollution, and the term is often used to describe what might happen to a crop or its wild relatives when a GM variety of that crop starts to be grown in their proximity. But here I mean the genetic mixing of two previously isolated plant populations. As could happen, for example, when you regenerate two genebank accessions of an outcrossing crop side by side. Or when you cultivate an exotic variety of an agroforestry species near wild stands of the same species. Or when you use seed of a wild species from point A to help restore its numbers at far-away point B. The debate about whether genetic mixing is a good or bad thing for conservation has been going on for a while, of course. It is generally thought to be bad. But by coincidence three papers came across my desk this week which suggest that we should perhaps keep an open mind.
The first paper looks at an annual plant in California, Mimulus laciniatus. ((Sexton, J., Strauss, S., & Rice, K. (2011). Gene flow increases fitness at the warm edge of a species’ range Proceedings of the National Academy of Sciences, 108 (28), 11704-11709 DOI: 10.1073/pnas.1100404108)) The researchers compared the progenies of different kinds of crosses in a common garden experiment to measure their overall fitness. They crossed plants from populations at the centre and at the warm periphery of the distribution of the species in various combinations. The most successful crosses, in terms of lifetime reproductive success, were between plants that came from different edge populations. So in this case, a little bit of pollution is actually a pretty good thing, if it comes from the right place.
The second paper looks at a long-lived woody shrub in Australia, Telopea speciosissima. ((Rossetto M, Thurlby KA, Offord CA, Allen CB, & Weston PH (2011). The impact of distance and a shifting temperature gradient on genetic connectivity across a heterogeneous landscape. BMC evolutionary biology, 11 PMID: 21586178)) There’s a lot of different aspects to the study, but let me focus on just one. The species is found along an altitudinal transect. There is considerable genetic structure along this transect, and a close association between altitude, temperature and flowering time. Altitude influences flowering phenology, differences in which throw up a temporal reproductive barrier between coastal and upland populations, leading to genetic differentiation. But not as much as formerly. The current temperature gradient is much flatter than it used to be at glacial maximum, and this has led to phenological overlap and genetic mixing at intermediate altitudes. What’s happening is a natural version of the centre x edge crosses done artificially in the previous paper. The fitness result? The authors are not sure. Could be good, could be bad. They’re going to set up the experiments to find out.
And finally we have a paper on the use of natural hybrids in forest restoration. ((Frascaria-Lacoste, N., Henry, A., Gérard, P., Bertolino, P., Collin, E., & Fernández-Manjarrés, J. (2011). Should Forest Restoration with Natural Hybrids Be Allowed? Restoration Ecology DOI: 10.1111/j.1526-100X.2011.00804.x)) This really ups the ante. We’re no longer talking about the kinds of intra-specific hybrids found at the admixture front at mid-altitudes in the previous paper, or the progenies of the artificial crosses between populations made in the first. We’re talking about hybrids between related tree species. Genetic pollution squared. The authors point out that “restoration programs rarely use local hybrid individuals if a local species exhibits natural hybridization.” But they think they should.
…our current research based on ecophysiological measures of water-use efficiency under controlled conditions on seedlings from these populations suggest that hybrids deal with drier conditions better than either parental species, a trait that could be important for climate change adaptation.
So, should we be a bit more relaxed about genetic pollution? The debate can only intensify as the need for species and habitat restoration, and perhaps assisted migration, increases with climate change. Perhaps we should start by choosing a less value-laden term for it.
Gender inequity in agroforestry seed supply
You may remember that in
last this week’s Brainfood we linked to a paper which looked at agroforestry input supply systems, and recommended a commercial, decentralized model for getting high quality tree seeds to smallholders. Now I’ve come across “Gender and agroforestry in Africa: a review of women’s participation.” The bottom line — not surprisingly, alas — is that women’s participation tends to be lower in enterprises in which there’s more money at stake. But this second paper only looked at the outputs, not the inputs. It would be interesting to know whether women tend to be edged out of commercial tree seed supply enterprises too. I suspect they do, which suggests that following the recommendation of the first paper for tree seed supply systems might result in even more pronounced gender inequity. So what could be done about it? Both papers include ICRAF staff as co-authors, though there’s no overlap. Maybe some of them have already thought about this and might like to comment here.
Nibbles: Beetles, Assisted migration, Potato breeding, Chaffey, Malnutrition
- Beetles good for weeds. No news on effect of Rolling Stones on pests.
- When to move species. Acacias, for example?
- A gene to prevent inbreeding depression in potato. I’m kinda down myself today.
- As you were, Plant Cuttings has made me feel a whole lot better.
- Documenting Peru’s success in fighting malnutrition. Did fortification play a role? Hard to say from this, which focuses on policy, and in particular conditional cash transfers.
Brainfood: Chinese landscapes, Agroforestry seed, Italian lentils, Carrot heterosis, Taro in islands, Indian wheat, AnGR ex situ, Woodland shrines, Vitamin A, Caraway, Adansonia, Neotropical blueberries, Yeast genetics, Rotations
- Agricultural landscapes and biodiversity in China. Traditional farming practices good for biodiversity, modern bad. Therefore need intensification, to take pressure off natural habitats. But no, wait, that usually means monocultures and chemicals, which are bad. Oh crap. No mention of genebanks.
- Innovation in input supply systems in smallholder agroforestry: seed sources, supply chains and support systems. Decentralized commercial system probably best for getting quality agroforestry seed to smallholders. Unfortunately, nobody listening.
- Characterization of Italian lentil (Lens culinaris Medik.) germplasm by agronomic traits, biochemical and molecular markers. I object in principle to any paper that says a particular landrace is “the best.”
- The relationship between heterosis and genetic distances based on RAPD and AFLP markers in carrot. It is positive. Was this really not known before in carrots? What am I missing?
- Genetic diversity of taro (Colocasia esculenta (L.) Schott) in Vanuatu (Oceania): an appraisal of the distribution of allelic diversity (DAD) with SSR markers. 10 villages, 344 landraces, 324 distinct multilocus genotypes, genetic pattern reflects social networks. Situation in Andaman Islands not quite so interesting.
- A study of genetic diversity among Indian bread wheat (Triticum aestivum L.) cultivars released during last 100 years. More diversity after Green Revolution than before, but steadily decreasing.
- Ex situ conservation genetics: a review of molecular studies on the genetic consequences of captive breeding programmes for endangered animal species. Restricted access, and you know what? I couldn’t care less.
- Consequences of wooded shrine rituals on vegetation conservation in West Africa: a case study from the Bwaba cultural area (West Burkina Faso). I expect there are some, but with restricted access, what’s the point of even linking?
- Evaluating sweet potato as an intervention food to prevent Vitamin A deficiency. To have an effect, you’d have to replace all the other types with orange-fleshed ones. Well, almost. Wonder whether it will be presented at the “International Scientific Symposium on Food & Nutrition Security Information: From valid measurement to effective decision-making” early next year.
- Evaluation of variability of morphological traits of selected caraway (Carum carvi L.) genotypes. They’re actually breeding this stuff in Poland. But they had to get their germplasm from botanical gardens around Europe.
- Variation in baobab seedling morphology and its implications for selecting superior planting material. There is some.
- Edible Neotropical blueberries: antioxidant and compositional fingerprint analysis. The 5 species involved have different ones.
- Population genomics and speciation in yeasts. There’s a question as to whether yeast species in fact exist in any meaningful sense.
- Cereal–forage rotations effect on biochemical characteristics of topsoil and productivity of the crops in Mediterranean environment. Continuous cereal stressed the soil.