Category: Wild relatives

Posted on

Climate change will cause more than extinction

A comment in Conservation Biology this month ((D.K. Skelly et al. (2007) Evolutionary Responses to Climate Change. Conservation Biology 21 (5), 1353–1355. doi:10.1111/j.1523-1739.2007.00764.x)) criticizes a recent paper in the same journal ((J.R. Malcolm (2006) Global Warming and Extinctions of Endemic Species from Biodiversity Hotspots. Conservation Biology 20 (2), 538–548. doi:10.1111/j.1523-1739.2006.00364.x)) which estimated that up to 43% of the endemic biota in some biodiversity hotspots could go extinct as a result of global climate change.

While not disputing that climate change will cause extinctions, the authors of the comment suggest that the climate envelope approach to predicting range changes ((That’s the same kind of approach that’s been used by our friend Andy Jarvis and others to predict dire consequences for the wild relatives of the peanut, potato and cowpea.)) ignores the possibility that species may in fact evolve in response to changes in the climate. And they quote evidence that such genetic change is happening.

Continue reading “Climate change will cause more than extinction”

Posted on

A history of viruses

We’re fond of reminding ourselves here that agrobiodiversity isn’t just crops and livestock and their wild relatives — it’s also pests and pathogens and weeds and pollinators and earthworms and brewer’s yeast. It’s one of our leitmotifs. Another is that agricultural and “wild” biodiversity interact. Here’s a paper that kind of brings these two leitmotifs together, into a sort of counterpoint, if I may be allowed to push the metaphor ((C.M. Malmstrom et al. (2007) Barley yellow dwarf viruses (BYDVs) preserved in herbarium specimens illuminate historical disease ecology of invasive and native grasses. Journal of Ecology (OnlineEarly Articles). doi:10.1111/j.1365-2745.2007.01307.x)).

Carolyn Malmstrom and her team at Michigan State University isolated RNA of barley and cereal yellow dwarf viruses from old herbarium specimens of Californian grasses, dating back to 1917. They used such historical samples to trace the history of these agriculturally important viruses back through time, building up a sort of family tree. The analysis suggests that the viruses were present in the Californian native flora in the 18th and 19th centuries, when invasive Eurasian annual grasses (some of them weedy crop relatives) displaced native perennial grasses. In fact, they may have facilitated this invasion by helping the exotic grasses outcompete the natives ((“Non-native invaders amplify spring aphid populations and increase BYDV infection in natives, which in turn suffer substantially reduced survivorship when infected.”)).

The team also found “potential correspondence in the timing of virus diversification events and the beginning of extensive human exchange between the Old and New Worlds.” Humans may have caused the branching of the family tree of some viruses by moving them and their hosts around the world.

Here’s Malmstrom on the significance of her work:

This work points out that the virus world does have an active, long-term role in nature, not just in agriculture… We very much need to understand how viruses can move and influence our crops. If we care about our crops, we need to care about what’s happening in nature.

So: aphids, viruses, native grasses, exotic weedy invaders, crops. Quite a fugue.

Posted on

Culling badgers backfires

There’s been a lot of news and discussion recently in the UK on animal diseases such as mad cow, foot and mouth, and bluetongue. Here’s another one to worry about: bovine tuberculosis. A paper just out in the Journal of Applied Biology explores the interaction between agricultural and wild biodiversity in the context of the spread of this disease in the UK ((H.E. Jenkins et al. (2007) Effects of culling on spatial associations of Mycobacterium bovis infections in badgers and cattle. Journal of Applied Ecology 44 (5), 897–908. doi:10.1111/j.1365-2664.2007.01372.x)).

Bovine tuberculosis can be spread by badgers, which have therefore been routinely culled for some years in many areas. But it turns out that badgers are in fact more mobile and adventurous in areas where their numbers have been thinned out. Which means they are most effective in spreading tuberculosis to cattle in exactly those areas where measures have been taken which were supposed to control the disease. The law of unintended consequences in action, I suppose.

Meanwhile, a big cull of feral pigs is on in Australia. ((Our occasional contributor Michael Kubisch wrote an interesting post on feral animals a few months back.)) Is this going to have some unintended consequences too?

Posted on

The Cretaceous roots of agriculture

A comment on a long but fascinating post on yeast genetics and evolution at The Loom sent me to a New Scientist article from a couple of years back which is perhaps more immediately relevant to our agricultural biodiversity focus here.

Some time in the distant past Saccharomyces cerevisiae, to give it its full name, developed a chemical trick that would transform human societies. Some anthropologists have argued that the desire for alcohol was what persuaded our ancestors to become farmers and so led to the birth of civilisation.

The article goes on to describe how brewer’s yeast evolved its somewhat surprising abilities. It turns out that its peculiar habit of carrying out anaerobic respiration even in the presence of oxygen — at a steep energetic cost, and resulting in the production of what is usually a poison, alcohol — dates back to an accidental duplication of its genome back in the Cretaceous. Eighty million years ago later, bakers and brewers are daily taking advantage of a genetic mistake that took place in a microscopic fungus when dinosaurs ruled the Earth. Isn’t agrobiodiversity wonderful?