Greg Baute has a post up at his blog on the Genomics of Genebanks Workshop held last week at the Plant and Animal Genome Conference. Interesting observations on core collections, comparing past genebank collections to current diversity in the field, and the role of crop wild relatives in breeding. I particularly liked Cameron Peace’s advice on how to get the most from collections of wild relatives of fruit trees. Maybe we’ll hear more about that at Davis in March.
Of cattle and people. And barley
Dienekes, a blogger who specializes in molecular anthropology, has a quick note today on a paper on the molecular genetics of cattle in Europe. The main story is one of distinction between North and South.
Apparently, the expansion of the dairy breeds have created, or largely maintained, a sharp genetic contrast of northern and southern Europe, which divides both France and Germany. It may be hypothesised that the northern landscapes, with large flat meadows, are suitable for large-scale farming with specialised dairy cattle (Niederungsvieh, lowland cattle), whilst the mixed-purpose or beef cattle (Höhenvieh, highland cattle) are better suited to the smaller farms and hilly regions of the south. However, it is also remarkable that in both France and Germany the bovine genetic boundary coincides with historic linguistic and cultural boundaries. In France, the Frankish invasion in the north created the difference between the northern langue d’oïl and the southern langue d’oc. The German language is still divided into the southern Hochdeutsch and northern Niederdeutsch dialects, which also correlates with the distribution of the Catholic and Protestant religions. On a larger scale, it is tempting to speculate that the difference between two types of European cattle reflects, and has even reinforced, the traditional and still visible contrast of Roman and Germanic Europe.
It doesn’t seem that the strong latitudinal genetic differentiation in cattle is matched by one in human populations. Here the pattern is much more gradual and clinal. ((Maybe there’s more interbreeding among human populations than between cattle breeds?)) However, there may be a similar “sharp genetic contrast of northern and southern Europe” (or at least between the Mediterranean and the rest of Europe) for barley. ((Yeah, I know it’s an old paper, but it’s the only map of barley genetic diversity in Europe I could find online at short notice. No doubt our readers will send in better examples.))
I’d dearly love to have the time to find out whether other livestock and crops show a similar pattern.
Maize mystery solved
Joost van Heerwarden and co-workers ((van Heerwaarden J, Doebley J, Briggs WH, Glaubitz JC, Goodman MM, de Jesus Sanchez Gonzalez J, & Ross-Ibarra J (2010). Genetic signals of origin, spread, and introgression in a large sample of maize landraces. Proceedings of the National Academy of Sciences of the United States of America PMID: 21189301)) have solved a problem in our understanding of maize domestication. Previous work had shown that maize originated from Balsas teosinte, Zea mays subspecies parviglumis, a wild species that occurs in low and mid-elevation regions of south-west Mexico ((Matsuoka Y, Vigouroux Y, Goodman MM, Sanchez G J, Buckler E, & Doebley J (2002). A single domestication for maize shown by multilocus microsatellite genotyping. Proceedings of the National Academy of Sciences of the United States of America, 99 (9), 6080-4 PMID: 11983901)). This made the Rio Balsas area, where parviglumis occurs, the most likely area of maize domestication. This was corroborated by Piperno et al.‘s ((Piperno DR, Ranere AJ, Holst I, Iriarte J, & Dickau R (2009). Starch grain and phytolith evidence for early ninth millennium B.P. maize from the Central Balsas River Valley, Mexico. Proceedings of the National Academy of Sciences of the United States of America, 106 (13), 5019-24 PMID: 19307570)) discovery of 8,700 years old maize remains in that area; the oldest evidence of maize unearthed to date.
The problem was that the maize land races genetically most similar to parviglumis are not found there. They occur in the Mexican highlands. And that’s awkward, particularly because highland maize has a rather different set of ecological adaptations than lowland maize.
Van Heerwaarden et al. say this is a paradox caused by the role of another wild species: Zea mays subspecies mexicana. This species occurs in the highlands, and it is inter-fertile with cultivated maize. The tricky thing is that because the two wild species, parviglumis and mexicana, both referred to as teosinte, are closely related, more closely to each other than to their cultivated cousin, geneflow from mexicana makes the genes of highland maize look more like those of parviglumis!
This means that you cannot directly identify the most ancestral maize populations from genetic similarity with their putative ancestor. Instead, Van Heerwaarden et al. estimated ancestral gene frequencies from cultivated maize populations, without direct reference to the wild species. And, Bingo! Western lowland populations are indeed more ancestral than the highland populations. Maize did originate in the lowlands, and from there it spread to the highlands and to other parts of the Americas.
Nibbles: Oranges, Pigs, Roundup, Agave
- The Human Flower Project uses Christmas oranges to teach about diversity and traditional knowledge.
- The New York Times discovered the hairy Hungarian Mangalitsa pig … so it must be real.
- SciDev.net’s highs and lows of 2010.
- “The genetic resources from landraces ignored by the tequila industry may be valuable for both ethanol production and conservation.” Uh-huh. h/t Jacob.
Nuts for pears
A funny thing happened to Dave Arnold on his globe-trotting effort to sample the apples of the world: he got waylaid by the pears. What happened next is the subject of a truly wonderful blog post that highlights his enthusiasm and ability to convey subtleties of the eating experience. Not bad for a chap who “helps chefs achieve their most ambitious goals using new technologies, techniques, and ingredients … including sous vide and hydrocolloids”. But of course, a trained mind and a trained palate can tackle anything, to whit:
- Cayuga … tasted of Nik-L-Nips ((Whatever they are. Ed.))
- Hermansverk 1/1 tasted of canned black California olives
- Perdue 41 was a dead ringer for giant water-bug essence
Seriously, this is a tour de force, and you know we don’t use that term lightly. The tragedy is that Brogdale makes next to no use of its riches.