Category: Genetic diversity

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Where to find seeds

This just in:

Thanks for putting Semilla Besada on your list of seed suppliers. I noted your comment that you could not find a list of seeds, and I am writing to explain why:) As our seeds are heritage or heirloom varieties, they are not on the EU approved list, so it is illegal to make them available for sale. So we have created a Heritage Seed Library, and are offering the opportunity for people living in dryland environments to swap seeds, so that we can keep the genetic biodiversity going, and extend those climate adapted varieties that suit dryland conditions to similar environments. Anyone interested should simply email us through the website. In the meantime, I will put up a link as Seed Swap Club so people can see more clearly how to contact us.

all the best,

Aspen

You can find Semilla Besada among the many links on our Seeds page. And if you know of sources that aren’t there, please share.

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They shoot horses, don’t they?

Ok, that’s just a provocative way of introducing an interesting review in Trends in Ecology and Evolution describing how harvesting from animal populations can affect their genetic make-up. 1 The following three types of genetic change are highlighted:

  1. strengthening or collapse of population structure
  2. genetic erosion
  3. selection

The take-home message is that management plans should recognize that harvesting changes not just the demography but also the genetics of populations. Very important for sustainable management of fisheries etc., but I bring it up here because it got me thinking: are any wild relatives of livestock exploited through harvesting? Things like these cute pigs, for example. And would the conclusions be very different for plants?

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Reindeer domestication

From our occasional contributor Michael Kubisch.

Reindeer have been domesticated by denizens of the Northern hemisphere for some time – but exactly for how long and  whether domestication occurred at different sites or only once has been the matter of some debate. Estimates of how long ago domestication might have happened have ranged from as long as 20,000 years ago to as little as 3000. Part of the problems stems from the lack of archaeological records that could pinpoint  a more exact time frame. The evidence for the shorter period relies mostly on ethnographic observation, such as the development of certain implements (for example saddles) that early reindeer herders developed apparently after contact with other people of the central Asian steppes.

But did domestication  happen more than once? A recent paper by a group of researchers from Oslo sheds some light on this question.  After analysis of a number of DNA markers they conclude that the Sami people of Northern Scandinavia domesticated reindeer independently from indigenous people in what is now Russia.  Moreover the evidence points to the existence of three distinct gene pools suggesting that domestication even within Russia may have occurred more than once.

And there  is another interesting observation: comparisons with gene markers from wild reindeer suggests that introgression of “wild” genes into domestic reindeer appears to have happened quite frequently through the ages,  but that only some of the  wild populations have made genetic contributions suggesting perhaps different propensities for domestication among animals of various wild herds.

Unfortunately there is increasing concern about the future of reindeer agriculture. The Sami herders, who live in Scandinavia, Finland and parts of Russia, are beginning to feel the effects of global climate changes. The rapid warming trend that seems to occur in the Northern hemisphere interferes not only with foraging but also with the ability to move animals across what used to be solid ice. And many Sami now fear not only the loss of their livelihood, but also the disappearance of a substantial part of the culture, which has always been intricately linked to reindeer.  

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Cassava diversity 101

After hanging out with experts for three days here in Cali, this is what I think I know about cassava genetic diversity:

  • There’s a hotspot in Brazil, but Central America is pretty diverse too. Those two places are also where the wild species are most numerous. There is geneflow between wild and cultivated populations.
  • There’s little geographic structure within the New World diversity, except for Guatemalan material being way genetically distinct (and higher in protein to boot). Lots of geneflow, I guess.
  • The African material is less diverse than the American, but not much, and significantly distinct from it. Selection, and isolation.
  • Within Africa, the Nigerian material is somewhat distinct. In general, there is more geographic structure in Africa than in the Americas.
  • Asia received material historically from both Brazil (via Africa) and Mexico (via the Philippines), but there hasn’t been the differentiation there that is seen in Africa. There hasn’t been as much selection of natural hybrids in Asia as in Africa.
  • Weird mutants keep turning up, including “sugary cassava,” “ketchup cassava” (the pinkiness is due to lycopene), and amylose-free clones.