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.
Showing posts with label fungi. Show all posts
Showing posts with label fungi. Show all posts
Thursday, September 13, 2007
Monday, July 16, 2007
Spontaneous order, fungal networks, and circuses
You wait ages to feel moved to post, and then three things come along at once. In no particular order…
Biological modularity can emerge as a spontaneous, self-organized process, say Ricard Solé and Sergi Valverde in J. R. Soc. Interface. By modularity they mean particular sets of interactions in the great web of biochemistry (rather than, say, organs):
Such a trend seems to call for an adaptive explanation. In particular, what seems to demand explanation are ‘motifs’ in these networks
Solé and Valverde cite a couple of adaptive explanations “based on a genetic programming approach”. But they don’t agree with them.
Instead, they say such modularity is the inevitable consequence of evolution by gene (or genome) duplication (“the driving force behind the evolution of complex organisms”, they say) followed by divergence, as evolution tinkers with the newly enlarged network of interactions (letting natural selection back in, it looks like)
I’ve clearly, as is my wont, become aware of this debate somewhere in the middle — the paper cites several is-modularity-evolution-or-is-it-self-organization? papers from the past few years. But, as far as I can tell, Solé and Valverde are saying that this is the first explanation for such modularity based on “fundamental, dynamical rules”.
In other network news, Proc R Soc B has just published a paper by Daniel Bebber et al. looking at fungal networks.
The challenges such a fungal mycelium faces are to explore its environment, exploit resources, transport them around the rest of the organism, and to be sufficiently robust to resist physical damage and the many fungus-eaters in the soil.
To investigate how fungi meet such challenges, they grew Phanerochaete velutina in the lab, growing it out from an inoculated lump of wood towards other lumps of wood. They found that the fungus began in exploratory mode, sending out lots of narrow filaments. But as it completed searching its environment it consolidated its resources into fewer, bigger bundles of hyphae, growing between maor resource patches, with more exploratory filaments in new territory, and crosslinks to provide some redundancy in the case of network damage. “Netowrk development”, say Bebber et al.
In other words, they’re stressing the diversity of different structures produced by flexibility and responsiveness to environmental variation, as much as whatever general laws such networks might have.
Philip Loring (who I believe blogs here) approaches questions of resilience, connectedness and persistence from a different angle in Ecology and Society. He proposes the circus as an icon of resilience, in that it has retained its identity while changing its contents — i.e. getting rid of freak shows and (mostly) animal acts.
The article, to my mind, contains a bit too much on the history of the circus, without exploring the implications of the circus-as-sustainability metaphor. Also, while ‘circus’ has survived for 200 years, most individual circuses haven’t. This is fine for institutions and systems, but not so much for species and ecosystems. But it’s a nice comparison.
Biological modularity can emerge as a spontaneous, self-organized process, say Ricard Solé and Sergi Valverde in J. R. Soc. Interface. By modularity they mean particular sets of interactions in the great web of biochemistry (rather than, say, organs):
Modularity is particularly obvious in cellular networks, where it can be detected at the topological level. These networks include the webs of interactions among proteins, genes, enzymes and metabolites or signalling molecules.
Such a trend seems to call for an adaptive explanation. In particular, what seems to demand explanation are ‘motifs’ in these networks
patterns of interconnections occurring in complex networks at numbers that are significantly higher than those in randomized networks.
Solé and Valverde cite a couple of adaptive explanations “based on a genetic programming approach”. But they don’t agree with them.
Instead, they say such modularity is the inevitable consequence of evolution by gene (or genome) duplication (“the driving force behind the evolution of complex organisms”, they say) followed by divergence, as evolution tinkers with the newly enlarged network of interactions (letting natural selection back in, it looks like)
I’ve clearly, as is my wont, become aware of this debate somewhere in the middle — the paper cites several is-modularity-evolution-or-is-it-self-organization? papers from the past few years. But, as far as I can tell, Solé and Valverde are saying that this is the first explanation for such modularity based on “fundamental, dynamical rules”.
In other network news, Proc R Soc B has just published a paper by Daniel Bebber et al. looking at fungal networks.
they have evolved to explore and exploit a patchy environment rather than ramify through a three-dimensional organism. Unlike all the other biological transport systems studied, the fungal network is not part of the organism, it is the organism.
The challenges such a fungal mycelium faces are to explore its environment, exploit resources, transport them around the rest of the organism, and to be sufficiently robust to resist physical damage and the many fungus-eaters in the soil.
To investigate how fungi meet such challenges, they grew Phanerochaete velutina in the lab, growing it out from an inoculated lump of wood towards other lumps of wood. They found that the fungus began in exploratory mode, sending out lots of narrow filaments. But as it completed searching its environment it consolidated its resources into fewer, bigger bundles of hyphae, growing between maor resource patches, with more exploratory filaments in new territory, and crosslinks to provide some redundancy in the case of network damage. “Netowrk development”, say Bebber et al.
involves over-production of links and nodes in the exploratory phase, followed by selection and positive reinforcement of some links and recycling of the remainder during the consolidation phase … A
similar sequence of events is apparent in the development of other biological transport networks including those formed by acellular slime moulds [and] foraging ant trails … and may well represent a universal feature of self-organized biological networks. However, in each of these systems, the final network structure is likely to represent a context-specific balance between the need for efficient transpor t, cost and robustness.
In other words, they’re stressing the diversity of different structures produced by flexibility and responsiveness to environmental variation, as much as whatever general laws such networks might have.
Philip Loring (who I believe blogs here) approaches questions of resilience, connectedness and persistence from a different angle in Ecology and Society. He proposes the circus as an icon of resilience, in that it has retained its identity while changing its contents — i.e. getting rid of freak shows and (mostly) animal acts.
Through the many forms they have taken over the last 150 yr, circuses have changed significantly while sustaining a singular identity. As a successful and enduring social system, their intriguing history exposes the nuances of sustainability theory, from resilience to pathologies, and illustrates that sustainability requires a complex dynamic between identity, tradition, and change.
The article, to my mind, contains a bit too much on the history of the circus, without exploring the implications of the circus-as-sustainability metaphor. Also, while ‘circus’ has survived for 200 years, most individual circuses haven’t. This is fine for institutions and systems, but not so much for species and ecosystems. But it’s a nice comparison.
Wednesday, April 11, 2007
Father and son
Among the many, many stories I've recently written for news@nature.com recently is one about changing dates of the UK mushroom season. There's been a huge effect in response to warming — the autumn season is twice as long, and some mushrooms are popping up in spring, as well as autumn.
This is a lovely example of you-never-know-when-it'll-come-in-handy data collection. The data — ranging from 1950-2005 — were collected by Edward Gange, stonemason by day and fungal recorder for the Wiltshire Natural History Society in his spare time. The lead author on the paper is his son, ecologist Alan Gange. Isn't that nice?
Another good thing about this piece is that it gave me a gave me a chance to interview Andy Overall, one of whose fungus forays I attended last year.
Back in the dim'n'distant, I had a lot of fun writing a longer piece for Nature about ecologists using data collected by amateurs to measure the effects of climate change on living things. If you ask me, this is probably the most important ever non-specialist contribution to science. Always glad to hear of any other candidates, though.
This is a lovely example of you-never-know-when-it'll-come-in-handy data collection. The data — ranging from 1950-2005 — were collected by Edward Gange, stonemason by day and fungal recorder for the Wiltshire Natural History Society in his spare time. The lead author on the paper is his son, ecologist Alan Gange. Isn't that nice?
Another good thing about this piece is that it gave me a gave me a chance to interview Andy Overall, one of whose fungus forays I attended last year.
Back in the dim'n'distant, I had a lot of fun writing a longer piece for Nature about ecologists using data collected by amateurs to measure the effects of climate change on living things. If you ask me, this is probably the most important ever non-specialist contribution to science. Always glad to hear of any other candidates, though.
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