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domestication

Turkey Domestication

Wild turkeys photo: sanbeiji, flickr (click to see in original context)

When I first saw the headline I was hoping I’d find an article describing the first fruits of the turkey genome project (which I talked about back in november.) Instead, and still interestingly, what was just published in the Proceedings of the National Academy of Sciences was a study showing that wild turkeys have been domesticated twice by different cultures in the Americas.

The turkeys we eat today come from a breed domesticated by the Aztecs, living in present day Mexico (or proceeding cultures occupying that region). However this study, looking purely at mitochondrial DNA sequences was able to use DNA isolated from bones and turkey droppings to determine that turkeys kept by indigenous farmers in what is now the American southwest represented an independent domestication of wild turkeys from one of a couple of wild turkey subspecies found in North America. Given the uncertainties of archeological dating, the most recent evidence for the existence of this second form of domesticated turkey could be as early as 1400 AD or as late as 1840 AD.

The Cliff Palace, the largest of the ancient villages in Mesa Verde Park. Photo: j-fi, flickr (click to see photo in original context)

What’s fascinating to me is (more…)

The Domestication of Maize

Twenty thousand years ago, not a single crop species existed in its current form. Almost* every bite of food you eat today is the result huge amounts of human artificial selection, both unconsciously and intentionally by farmers and plant breeders. Sometimes the obvious changes are minor, for example between wild and domesticated strawberries:

Wild strawberry (left) and domesticated strawberry (right)

Wild strawberry (left) and domesticated strawberry (right)

Clearly one of the major traits early strawberry growers selected for was bigger fruits. Which makes sense since it takes about the same amount of time an effort to pick a strawberry either way, but if you’re picking the ones on the right you’ll have more pounds of fruit picked at the end of the day.

But even in this case, the similarity in form hides major changes at the genome left. Strawberries went through two whole genome duplications during domestication (looks like it’s more complicated than I made it sound see comments), so each of the cells in the strawberries on the right contain eight copies of each chromosome, while the strawberry on the left contains the more standard two copies of each chromosome.

On the other end of the spectrum is maize. (more…)