Category: Wild relatives

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A new use for tubers

A sharp knife is an essential element in the preparation of many vegetables, a fact as true 2 million years ago as it is today. Results from the recent meeting of the Paleoanthropology Society, reported in Science, indicate that the people who occupied the site of Kanjera South in Kenya carried stones that held an edge better from at least 13 kilometres away. Thomas Plummer of Queens College in New York and David Braun of the University of Cape Town found that a third of the stone tools at Kanjera came from elsewhere, and that these stones made longer-lasting knives than local material.

What were they using the knives for? To butcher animals, obviously, but also to cut grass and to process wild tubers. Cristina Lemorini of La Sapienza university here in Rome showed that the pattern of wear on the ancient tools matched the wear on modern stone tools used by the Hadza people of Tanzania to process plant material. In particular, using the stone knives to cut the underground storage tubers of wild plants left a pattern of grooves and scratches that was identical on modern and two-million year old stones.

Why tubers? There have been lots of theories about the role of plant tubers in the evolution of humanity, most of which hinge on the energy to be obtained from tubers, especially when times are hard. Margaret Schoeninger, of the University of California, San Diego, floated an intriguing new idea at the meeting. She noted that most of the tubers provide scant energy, and that modern Hadza chew on slices of tuber but don’t swallow the fibrous quid. Measurements show that panjuko (Ipomoea transvaalensis) and makaritako 1 can be up to 80% water. Schoeninger thinks that early humans used the tubers as portable canteens.

That might raise the question: why weren’t they domesticated? That’s an unanswerable hypothetical, but the simple answer might be that there was just no need to.

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Botanical garden database heaven

An email alert from the good folks at Botanical Gardens Conservation International (BCGI) tells me they have spruced up their website. And the website in turns reminds me that May 18th is Plant Conservation Day, and we should probably do something about that here.

But the main reason for the alert is to draw our attention to two online databases: PlantSearch and GardenSearch.

PlantSearch enables users to locate rare or threatened plant species in cultivation around the world. This database is compiled from lists of living collections submitted to BGCI by the world’s botanic gardens. The database presently includes over 575,000 records representing almost 180,000 taxa from 692 gardens.

And you can find a garden anywhere in the world using GardenSearch, with over 2658 records. We’re working on an interactive botanic garden mapping tool too…

There’s a filter for crop wild relatives. Seems to me the botanical gardens community may be a bit further down the road out of database hell than the world’s genebanks.

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“A man is related to all nature”

Mark Easton, the BBC’s home editor, starts a blog post today with this quotation from Ralph Waldo Emerson as an introduction to making the point that the protected area of Wicken Fen in Lincolnshire is… 2

…the product of complex interaction between plants, birds and animals. And fundamental to its existence were the apparently destructive activities of one animal in particular: man.

Well, that could be said of a lot of landscapes around the world. Even, possibly, as is increasingly argued, places like the Amazon, which until recently was generally regarded as nature in its most pristine state.

But to go back to Wicken Fen, which, incidentally, I remember very fondly, having done a certain amount of fieldwork there as an undergraduate. It seems “the [UK] government, anxious to protect another fragile habitat, the peat bog, wants 90% of composts and soil improvers to be peat-free by next year.” So peat digging was banned at Wicken Fen. Good, you say? Well, not so much. This change in a practice that has been going on for centuries has contributed to the local extinction of the rare fen orchid. And not only that, the fen violet too, probably:

The rural culture – which had cut the sedge for roofing and animal bedding – disappeared and the fen violet along with it. Its seeds may still survive in the peaty soil and occasionally a rare plant will push through the surface if the land has been disturbed, but the violet has not been seen at Wicken for more than a decade.

And the swallowtail butterfly and Montagu’s harrier as well, due to past changes in management practices.

So what to do. As Mark Easton says, nowadays “conservationists ape the principles of the ancient harvesters to protect what is left of the fen.” But not all agree. “Instead of trying to counteract nature, man should work with it.”

This is a much less predictable approach to conservation but, it seems to me, it is a philosophy more in tune with an acceptance that man is not god. We are part of nature too.

Fair enough, but what if you are managing a protected area specifically for a particular species of value? Say an important crop wild relative. I can imagine a situation where you might want to be a bit more intensive in your intervention, and a bit more predictable. Which is one of the reasons why I don’t think that “conventional” protected areas such as your average national park will ever be much use for CWR conservation, except by chance.

Incidentally, there’s a couple of CWRs at Wicken Fen, according to the great mapping facility on its website. Here’s where you can find Asparagus officinalis, for example: it’s that red square right at the top.

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Tahr protected, but wild carob?

WWF is announcing the establishment of a national park in the United Arab Emirates for the Arabian Tahr. Tahr are wild goats, but I think perhaps it may be pushing it to describe them as livestock wild relatives. Maybe a livestock expert will tell us.

In any case, the Arabian Tahr does share a habitat with at least one crop wild relative, Ceratonia oreothauma ssp. oreothauma. I believe that’s the only other species in the carob genus. I’ve actually collected the damn thing in Oman, and not at all easy it was too. But was an opportunity missed of making this a joint livestock-and-crop-wild-relative protected area?

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How to rescue a sunflower wild relative

A paper by Jennifer R. Ellis and David E. McCauley of Vanderbilt University, just out in Biological Conservation, tries to answer a couple of quite controversial questions for conservationists: 3 How do you prioritize populations for conservation? And when does genetic pollution become genetic rescue? Both answers depend on something most gene-jockeys don’t do much of: growing plants and seeing how they perform.

To add piquancy, the paper deals with a crop wild relative, and a very rare one at that: Helianthus verticillatus, which is known from only four sites in the southeastern United States. The authors worked on populations from two of these, in Tennessee (fewer than 100 individuals) and Alabama (several hundred individuals). They collected seeds from sixteen of what they had previously identified as genetically distinct individuals from each population, and then made a whole bunch of crosses, both within populations and also between the two populations, for two generations. They grew the progeny of these crosses in the same environment and measured how well they did in terms of fruit viability, germination, survival and pollen quality.

So, first, to the prioritization question. Genetic markers are now routinely used to identify populations that are particularly low in diversity and thus in need of immediate in situ protection or collecting for ex situ conservation. Often, genetic diversity is positively correlated with fitness, but this is not always the case. For H. verticillatus, in fact, it was known from previous marker studies that the two populations had comparable levels of genetic diversity and only moderate genetic differentiation. However, the results of the common environment study on the offspring of the intra-population crosses showed that they different significantly in their overall “fitness,” with the Tennessee material having lower germination rates and fruit viability. In other words, molecular markers on their own would not have raised a particular concern about the long-term viability of the Tennessee population. In the words of the authors, “contrary to genetic marker information, these populations are not interchangeable with regard to quantitative fitness characters.”

Next, the genetic rescue question. The conventional wisdom of course is that conservation should strive to maintain the genetic integrity of populations. Bringing in material from elsewhere constitutes genetic pollution and is BAD. The introduction of new genetic material into relatively homogeneous populations with low fitness can of course result in heterosis and increased fitness. But it can also lead to lower fitness — inoutbreeding depression — “owing to the dilution of local adaptations or disruption of co-adapted gene combinations.” Enter the inter-population crosses. Crossing Tennessee individuals with those from Alabama resulted in offspring that were more fit, with no sign of outbreeding depression, at least for the two generations of the study. This “offers great promise” as an active conservation strategy for the Tennessee population, the authors say.

Given people’s sqeamishness about messing around with rare species, I wonder if such activism will be given a chance.