Category: Wild relatives

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Forced penning in the Sahara

Mathilda had a post a few days ago which caught my eye, but I forgot to nibble it. Better late than never. She discusses a recent paper reporting on the archaeological excavation of Uan Afuda and other Early Holocene sites of the Acacus mountains, in the Libyan Sahara, and in particular the layers of animal dung that excavations uncovered. The paper suggests that these “dung layers are related to a forced penning of a ruminant, very likely Barbary sheep (Ammotragus lervia),” and that this is evidence of delayed use of resources designed to cope with lean periods. Mathilda goes on to hypothesize that cattle domestication keeping ((See comment from Mathilda.)) may have started in the Sahara — before the growing of crops — in a similar way.

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Movable feasts

There’s no doubt that climate change poses a huge challenge for in situ conservation of species — including crop wild relatives — in protected areas. I mean, what is one to do, move the park around to follow the species as it tracks the climate? Well, that’s exactly the type of thing that marine biologists are now contemplating for Marine Protected Areas (MPA):

Maybe they’re bigger, … or spaced like stepping stones so species can hopscotch to higher latitudes. Perhaps they’re not tied to a geographic location at all, but follow conditions scientists know are important.

We saw in earlier posts that assisted migration could be another approach. A couple of things are for certain. If protected areas are aimed at individuals species, as opposed to the landscape or ecosystem, we’re going to have to rethink how we define and manage them. And ex situ conservation will be an increasingly important complement to them.

“We set aside parts of the world as if it’s going to be static,” says [Dee] Boersma, at the University of Washington, Seattle. “But the one thing that’s constant is change.”

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Critically endangered cassava wild relative delays rotting

Here’s something else I learned at this workshop I’m attending on the state of plant genetic resources conservation and use in Latin America:

Dramatically delayed PPD [postharvest physiological deterioration] was found in Manihot walkerae, a wild relative of cassava found in Mexico and USA (state of Texas) (Fregene and Mba 2004). An accession of M. walkerae (MWal 001) was crossed extensively to elite cassava varieties. A single successful genotype was found with delayed PPD. The storage roots of the hybrid remained intact a month after harvest. Backcrosses of this hybrid to elite progenitors of the CIAT cassava gene pools and selfed (S1) populations were made for genetic mapping of the delayed PPD traits.

This came up during a discussion of the importance of collecting and conserving crop wild relatives. I had no idea the Manihot genus went as far north as Texas. Walker’s manioc turns out to be extremely endangered:

Until recently, it was believed that this species was represented in the U. S. by a single plant in the wild, discovered in Hidalgo County in 1990. In 1995, Walker’s manioc was located in three different areas on the Lower Rio Grande National Wildlife Refuge in Starr and Hidalgo Counties.

It is known from only a couple of populations in Mexico. I don’t give much for its chances in the wild. But there is material in the San Antonio Botanical Garden. And some of its genes are now in some cultivated varieties.