Do escaped transgenes persist in nature?

Of the things I get worked up over, genetically modified crops aren't that high up the list. (As an aside, I think the UK farm-scale trials of a few years back did a good job in showing that GM crops tended to reduce agricultural biodiversity, but that this was a result of the changes in farming methods associated ith them, rather than any property of the crop per se. Likewise, I think the issues around GM crops are more to do with big agribusiness controlling the food chain, loss of varietal diversity and so on, rather than that the technology is somehow immoral or that eating them is bad for you. It's striking that in places where they don't have the luxury of squeamishness about agriculture, such as India and China, GM is rather less of an issue.)

That said, I think this paper in Molecular Ecology by Suzanne Warwick et al is interesting. They show that herbicide resistance genes from oil-seed rape (Canola) have crossed into a weedy relative, Brassica rapa and set up home there (they've been there for 6 years, apparently).

"Most hybrids had the [herbicide resistance] trait, reduced male fertility, [and] intermediate genome structure", say Warwick et al. Whether they are more or less fit than the wild variety - and what consequences this has for the weediness of B. rapa - they don't say in the abstract. That's clearly something worth studying; I don't think panic is in order, but vigilance is, so well done to these researchers for playing the long game. Although by the time we find out we've created a super-weed it may be a bit late.

Sharks, sheep and viruses

Three recent conservation biology-type papers worth a look:

Do shark declines creat fear-released systems?
A model sugesting that if you take pacific sleeper sharks out of the ocean, seals swim deeper, and eat more pollock - which live deep - and fewer herring.

Are cattle, sheep, and goats endangered species?
The "rise of the breed" 200 years ago, followed by more recent selection for increased productivity has led to a dangerous drop in the genetic diversity of domestic animals. "Many industrial breeds now suffer from inbreeding, with effective population sizes falling below 50... It is therefore important to take measures that promote a sustainable management of these genetic resources; first, by in situ preservation of endangered breeds; second, by using selection programmes to restore the genetic diversity of industrial breeds; and finally, by protecting the wild relatives that might provide useful genetic resources."

(Andrew Marr says that whenever you see a newspaper headline ending in a question mark (Is this the most evil man in Britain?; Are working mothers poisoning their children? and so on) you should answer 'no'. I'm not sure if the same applies for the scientific literature.)

Barley yellow dwarf viruses (BYDVs) preserved in herbarium specimens illuminate historical disease ecology of invasive and native grasses
Invasive species are often thought to thrive because they escape all the diseases and predators that keep them in check back home. But this study suggests that the diseases that invaders bring with them are just as important as the ones they leave behind.

In California, over the past two centuries European grasses have almost completely displaced the native prairie. Carolyn Malmstrom and her colleagues think that one factor in their success was the viruses they brought with them. For example, they have previously shown that native grasses growing alongside exotics have higher levels of cereal yellow dwarf viruses.

But this doesn't put the viruses at the scene of the crime. Now they've taken a step towards that (although how you ever prove such an idea, I don't know). Using herbarium specimens from 1917, they have recovered some of the oldest plant viral sequences so far and, by comparing them with European relatives, show that the disease probably showed up along with the plants — and also hopped from California to Australia in the late nineteenth century — and may have been a useful ally in the invaders battle against the natives.

Underground networking

Todays's Nature contains a News Feature by me (behind a paywall, I'm afraid), looking at the possibility that mycorrhizal fungi transfer nutrients between plants, and in the process undercut the above-ground competition between plants by robbing the rich to feed the poor - subsidizing plants less able to photosynthesize.

How, why and whether they do this is still uncertain and occasionally controversial. But everyone seems to accept that mycorrhizal networks do exist - namely, that a single fungus can link many plants, potentially of different species, creating a arena for a rich range of ecological interactions. It's just we're not sure what they are. But a bunch of people are doing their damnedest to find out. Mycorrhizal ecology looks like a funky (and fungi) field right now.

For a more technical (than my piece), but freely accessible introduction to this field check out this TREE paper.

Feed the trees

How good are forests at soaking up carbon, and how much will they buffer greenhouse gas emissions and save us from climate change?

It's an extremely knotty question — and so this review (open access) of the issue just published in New Phytologist is extremely welcome. Increased CO2 should be a fertilizer, and things grow quicker in warm weather, but as temperature increases, the rate of respiration rises more quickly than the rate of photosynthesis, so the rate at which trees release more carbon rises more quickly than the rate at which they soak it up (this also has implications for metabolic ecology: by understanding these effects, via metabolic rate, you can build a bridge between cellular and individual metabolism and the workings of the global carbon cycle). Also, plant growth is limited by other things, so a lack of nitrogen, for example, may limit trees' ability to respond to higher CO2, or warmer temperatures.

The review, which looks at studies in boreal and temperate forests, concludes that we don't really know what's going to happen. Here's what they say…

It is not in doubt that newly established young forests will continue to be C sinks for the foreseeable future. The key question is whether the mature forests that are C sinks today will continue to be sinks as the climate changes. … Forest ecosystem models indicate that the additional terrestrial sink arising from global climate change is likely to be maintained in the short term (over several decades), but may gradually diminish in the medium term. … Because of current limitations on our understanding with respect to acclimation of the physiological processes, the climatic constraints, and feedbacks among these processes – particularly those acting at the biome scale – projections of C-sink strengths beyond a few decades are highly uncertain.

This seems a good argument against tree-planting carbon offset schemes.