Cattle’s great adventure

ResearchBlogging.orgEvolutionary Anthropology has a nice paper summarizing the history of domestic cattle, based on the latest molecular marker data. ((Ajmone-Marsan, P., Garcia, J., & Lenstra, J. (2010). On the origin of cattle: How aurochs became cattle and colonized the world Evolutionary Anthropology: Issues, News, and Reviews, 19 (4), 148-157 DOI: 10.1002/evan.20267)) Unusually, the authors at least attempt a flowing account of the origin and spread of a domesticated species, and even more unusually actually achieve it in places. Alas, the details of haplogroups and mtDNA vs Y-chromosome markers will keep intruding. Someone will write a review paper some day which gets the geeky stuff of summarizing all the molecular and other data out of the way upfront, and then just tells the story of domestication and dispersal as the old-fashioned, and no doubt now out of fashion, narrative historians used to do. Rather than annoyingly mixing up the two.

Anyway, that story can be summarized for cattle in one map, and here it is:

Which is cool enough. But actually what stays in the mind — or, at any rate, my mind — is, as ever, the little things. Here are three that did it for me.

First, a rare attempt to link up genetic patterns in a domesticated species and the associated human population:

Four ancient Tuscan breeds all had haplotypes also found in Anatolia, near the sites of domestication. [This] … may indicate a secondary migration from Anatolia to Italy, [which] … would be in line with the classical accounts of Etruscans arriving in Italy from either Lydia or the isle of Lemnos. An Etruscan representation of cattle resembles the semi-feral Maremmana cattle in southern Tuscany. Interestingly, inhabitants of two small Tuscan cities with Etruscan origins also had southwest-Asian mtDNA signatures.

Second, a simple historical explanation for a fairly obvious feature of modern European cattle diversity, to wit, that there isn’t much of it in the Netherlands.

Seventeenth-century Dutch paintings show cattle with a large variety of coat colors. After three catastrophic rinderpest epidemics in the eighteenth century, cattle herds were repopulated by mass imports of black-pied cattle from the Holstein region.

And finally, the story of the Brazilian zebu herd, which caught my eye because of the reference to it in a recent Economist article.

This started during the nineteenth century with the purchase of a few animals and was followed by mass imports of Guzerat (1975), Gir (1890), and Ongole (1895, in Brazil denoted as Nelore) animals to improve the national herds. The same zebu breeds were also imported into the U.S. These imports consisted mainly of bulls. The percentage of animals with zebu mtDNA varies in Brazil from 37% in the Gir breed to 43% in the Nelore and 69% in the Guzerat breeds. As shown by the distribution of the indicine Y-chromosomes and microsatellite analysis, zebu bulls were crossed in several South American Criollo populations… Today, Brazil holds the largest commercial cattle population worldwide, with 200 million heads. Together with descendants of other indicine and taurine imports, Nelore make up the bulk of this intensively managed population.

You see what I mean about the geeky stuff interrupting the flow, right? Anyway, the particularly fun detail about this Brazilian zebu story is the fact that one Nelore bull, called Karvadi, “became the ancestor of thousands of Brazilian zebu cattle.” There’s a photograph of him in the paper, courtesy of the Archives of the VR Artificial Insemination Center, Araçatuba, and very handsome he is too.

Putting high-tech breeding in more hands

New Agriculturist has a long report about marker-assisted selection and cowpea breeding. The gist of it is that cowpea is susceptible to Striga, or witchweed, a parasitic plant that can destroy the harvest totally. A resistance gene turned up in “an unimproved variety from Botswana” ((Where, bizarrely, Striga does not occur. Go figure.)) and is the basis of breeding programmes. Screening the results of crossing programmes conventionally is a nightmare, but a doddle if all you’re looking for is the presence of the resistance gene (or a marker close by). That, however, normally requires a well-equipped biotech lab. A UK charity, the Kirkhouse Trust, has been funding a consortium of cowpea breeders in west Africa with the specific aim of making marker-assisted selection available in the field.

The requirements for MAS boil down to a means of extracting DNA from the plant, and the equipment and reagents to then amplify the critical sequence in order to establish its presence or absence. The Trust’s priority has been to source reagents which do not require constant refrigeration and are not hazardous. DNA extraction has become a matter of squashing a leaf segment onto a specially treated paper, and the amplification reaction is provided in dry form, to which the user needs only to add water, and the DNA in the form of a small disc of paper.

One of the project’s six west African partners, in Burkina Faso, has made excellent progress and is now the focus of efforts and a training centre.

The key to the whole effort is the search for sustainability; the Trust believes that this is much more likely to be achieved by putting the technology directly into the hands of the practitioners, rather than by gifting it from on high. This way, the breeders themselves are more likely to have a stake in proving its worth and to be prepared to generate the internal pressure to incorporate MAS into their own national programmes over the long term.

I wonder, though, how many other valuable genes are hiding in unimproved varieties in Botswana and elsewhere. What about their sustainability?

Not the wheat genome sequence

The International Wheat Genome Sequence Consortium, an international consortium of wheat growers, public and private breeders and scientists, strongly disagrees with implications that the sequence reads made available by a UK team, led by Professor Neil Hall, represent in any way the sequence of the wheat genome or that this work is comparable to genome sequences for rice, maize, or soybean.

Ouch. Via.

Nibbles: Biotech to the rescue, Chinese horses, Soybean carotenoids, CropMobs, Nutrition, Coffee pests, Varroa, Berries, NUS

Nibbles: CIFOR, Weeds, Camelids, Drought, Biofortification, Buckwheat

  • CIFOR has a blog!
  • Nice series of videos on eating weeds.
  • Video on Peru’s “Andean rodeo.” You heard me.
  • Africa needs drought-tolerant maize. Ok, fair enough, but here’s my question. Shouldn’t they have done this study before doing all that breeding? Oh, who knows, maybe they did.
  • “Biofortification will thus remain relevant to poor rural populations in the years to come, as their incomes will still be far too low to afford a more diversified diet.” What? Who says a diversified diet need be expensive?
  • Russia faces looming buckwheat crisis. At least the genetic resources are safe in the Vavilov Institute. Unless of course somebody decides to, I don’t know, build luxury villas there, or something.