- Der Spiegel does its usual impressive number, this time on the Völkerwanderung. Via.
- Diversity and stability in grasslands. Yes, there’s a connection.
- Sheep breeds in India deconstructed.
- The future of the Guinea savannah. Probably not that great.
- IRRI teaches Singaporean cityslickers to grow rice.
- Silk beginning to fade where it was born.
- The diverse benefits of an agrobiodiverse diet. Should someone tell rich Indians?
- Tales of two giant inflorescences. What are the odds?
Nibbles: Abalone, Yak, Forests, Mountain plants, Yams, Ulmus, Apple, Banana
- We now know how to harvest abalone sustainably. Is there anything we cannot do?
- Wild yaks get assessed. Wait, there are wild yaks?
- “…forests played a central role in the rise of the modern state.” Not as flaky as it sounds.
- Andean plants at risk from, well, everything.
- Yams in Nigeria, from festivals to in vitro.
- London’s elms.
- “[L]ike biting into a perfume bottle, but without shards of glass piercing your tongue.” A knobbed russet.
- Banana evolution just got more complicated.
The revenge of history
Three papers today which look into the role of history in determining patterns of diversity, at the species and genetic level. I don’t have much time today, so descriptions will have to be quick and dirty for now.
In Molecular Ecology, Hoban et al. used microsatellites to genotype 29 populations of Juglans cinerea from throughout the eastern US. ((HOBAN, S., BORKOWSKI, D., BROSI, S., McCLEARY, T., THOMPSON, L., McLACHLAN, J., PEREIRA, M., SCHLARBAUM, S., & ROMERO-SEVERSON, J. (2010). Range-wide distribution of genetic diversity in the North American tree Juglans cinerea: a product of range shifts, not ecological marginality or recent population decline Molecular Ecology DOI: 10.1111/j.1365-294X.2010.04834.x)) They wanted to know whether the observed pattern of genetic diversity was best explained by the spread of the species from refugia after the last glaciation, by its recent dramatic decline due to a fungal pathogen, or by a core-vs-periphery effect. It turned out to be the first of these. One of the consequences is that southern populations are the most diverse, and should be the ones to be targeted for ex situ conservation in the face of the depredations of the fungus.
Meanwhile, over at the Journal of Applied Ecology, Reitalu et al. looked at species diversity in Swedish grasslands in relation to various aspects of management. ((Reitalu, T., Johansson, L., Sykes, M., Hall, K., & Prentice, H. (2010). History matters: village distances, grazing and grassland species diversity Journal of Applied Ecology DOI: 10.1111/j.1365-2664.2010.01875.x)) They found that distance to the nearest historical village was an excellent predictor of grassland diversity, integrating various management variables. Diversity peaked at 1-1.5 km from the nearest village, and declined thereafter with distance. This finding could be used to prioritize grasslands for conservation, and to devise appropriate management programmes, which should involve moderate grazing pressure.
Finally, again in the Journal of Applied Ecology, González-Varo et al. describe a somewhat retro study on the Mediterranean Shrub Myrtus communis in SW Spain using isozymes. ((González-Varo, J., Albaladejo, R., Aparicio, A., & Arroyo, J. (2010). Linking genetic diversity, mating patterns and progeny performance in fragmented populations of a Mediterranean shrub Journal of Applied Ecology DOI: 10.1111/j.1365-2664.2010.01879.x)) Working not only on the actual natural populations but also on progenies, they wanted to know the relative importance of the past and the present effects of fragmentation of populations on fitness. The past effects were represented by the genetic diversity of populations, the present effects by outcrossing rates. In contrast to the previous two papers, they found that the present is a better guide to conservation that the past. It was outcrossing rates that had the strongest effect on the fitness of progenies. The recommendation is for honeybee hives to be controlled in the vicinity of these populations, to foster a diverse assemblage of local pollinators, and thus increased outcrossing.
Great to see very clear conservation recommendations being made in all cases, solidly based on the results. It is not always so.
Digging up Carolina Gold
Many thanks to Robert for reminding me that we had talked about Carolina Gold before, and that the story of its Malagasy origin is not all that cut and dried.
The diverse uses of genebank collections
It’s easy to assume that it’s only plant breeders that use genebank collections. But in fact there are clever people out there who are delving into genebanks for all kinds of different reasons. Two recent articles on rice illustrate this nicely.
In the latest Rice Today Tom Hargrove tells the story of the global odyssey of the rice varieties called Carolina Gold and White.
Carolina Gold and White show how genes of good crop varieties spread. The seeds made a remarkable journey: from Indonesia to Madagascar by boat almost 2,000 years ago, then to the wealthy and slave-driven Carolina plantations. Her seeds seem to have helped war-weary Confederate veterans start a new life along the Amazon in South America. Freed slaves may have taken her seeds back to Africa, which she once called home. Carolina Gold recently started a new life in South Carolina, and her white-hulled sister is a parent of an improved variety for upland rice farmers in Colombia and Panama.
Hargrove describes how it was by comparing contemporary seeds with genebank samples that part of that epic story was pieced together, and how it was from genebank samples that Carolina Gold cultivation was revived, albeit it on a much smaller scale, in the State which gave it its name, after almost a hundred years.
Meanwhile, EurekAlert has a piece on another famous, though rather more modern, rice variety: IR8. One of the Green Revolution varieties,
IR8 used to produce 9.5 to 10.5 tons per hectare, significantly more than other varieties in the 1960s when average global rice yields were around only 2 tons per hectare. But, when grown today, IR8 can yield only around 7 tons per hectare.
Why? Is it nature or nurture? Researchers “grew rice from original IR8 seeds preserved in the International Rice Genebank and compared it to rice grown from IR8 seeds continuously grown and harvested over the last few decades.” Genetically, they were found to be similar, so the 15% decrease in yield must be down to environmental changes, possibly including hotter nights:
the findings demonstrate the need for ongoing or “maintenance” breeding because it allows rice plants to cope with a changing environment.
So, even when genebank accessions are not used by breeders, the results can end up being of use to breeders.