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Absolutely fascinating work! However, I'm not entirely sold on the usage of the term "mother tree." While Simard says > That’s how we came up with the term “

Absolutely fascinating work! However, I'm not entirely sold on the usage of the term "mother tree." While Simard says > That’s how we came up with the term “mother tree,” because they’re the biggest, oldest trees, and we know that they can nurture their own kin. the interview doesn't reference any work that specifically states these mother trees will preferentially nurture kin over other species. For example, when she describes the more controlled greenhouse experiment with Douglas firs and Ponderosa pines, an injured mother tree Douglas fir dumped carbon into the network and the ponderosa pines still absorbed it. She may have other work that describes some kind of kin preference, but I don't see it cited and I don't quite understand what the mechanism to make this happen would be. Rather, (as a layman without any knowledge of the work and published papers around this topic), I see this phenomenon not as the result of "mother trees" but from "farmer fungi." The fungi, because of their large networks and relationships with the trees, become "resource managers" of the forest. The fungi have an incentive to make sure that the trees are healthy and will continue to provide nutrients for the fungi. When younger trees are injured, that is a threat to the fungi's survival, and therefore one possibility is that they have evolved this mechanism that transports resources from older trees to the younger ones to help the younger trees survive. The relationship between these fungi and trees are normally symbiotic, but the older trees "tolerate" (or fail to evolve some immune response to) this mildly pathogenic behavior because it likely benefits its nearby offspring or close kin. I think the concept of the "mother tree" might be slightly anthropomorphic, assuming that a large, multi-organ plant must be more intelligent and possibly be even more caring than small fungi that must only be able to perform simple functions. In reality, the fungi are the organisms in the best position to evolve this beneficial behavior. Again, I'm a non-expert with zero knowledge on this topic. If anyone could provide a reference to a free online paper that describes these "mother trees" as preferentially nurturing kin, I could be persuaded. And that would be a very interesting read!

dmix 9y ago
This was the specific quote from the article: > In later experiments, we’ve been pursuing whether these older trees can recognize kin, whether the seedling that are regenerating around them are of the same kin, whether they’re offspring or not, and whether they can favor those seedlings — and we found that they can. That’s how we came up with the term “mother tree,” because they’re the biggest, oldest trees, and we know that they can nurture their own kin. It seems that Kevin Beiler was the one who did research about this so that may be a good place to start rather than the author. But whenever reading something like this quote below, where it's clearly a useful narrative for funding and public support, I find it's always good to be skeptical about how far that analogy extends: > We’ve got a lot of interest from First Nations groups in British Columbia because this idea of mother trees and the nurturing of new generations very much fits with First Nations’ world view.
schiffern 9y ago
These networks also transport signalling and defense molecules, which seem to transmit kin selection information. They also (as you might expect) work better on plants of the same species. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4497361/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4497361/ >The relatedness of neighbours in mono-specific plant communities can also influence whether MNs will elicit adaptive behavioural changes. For example, foliar nutrition in AMF Ambrosia artisifolia L. improved when it was integrated into an MN with related plants but not conspecific strangers (File et al. 2012). Likewise, in mono-specific pairs of EMF interior Douglas-fir grown in greenhouse conditions, foliar micronutrients were increased in kin compared with strangers grown with older conspecifics (Asay 2013). This appears to be linked with mycorrhizal association of this system as mycorrhizal colonization was also elevated in kin seedlings (File et al. 2012; Asay 2013). These findings reveal that MNs can play an integral role in kin selection, but the exact mechanisms by which they do this are unclear. However, there is strong evidence that biochemical signals derived from mycorrhizas or roots are involved. For example, Semchenko et al. (2014) showed that root exudates carried specific information about the genetic relatedness, population origin and species identity of neighbours, and locally applied exudates triggered different root behaviour responses of neighbours. This included increased root density, achieved through changes in morphology rather than biomass allocation, suggesting the plants limited the energetic cost of their behaviour. >Because the overwhelming majority of plants are predominantly mycorrhizal in situ, any root exudates involved in kin recognition are likely to be filtered through mycorrhizal fungi. In a recent study using stable-isotope probing, we found that MNs transmitted more carbon from older ‘donor’ Douglas-fir seedlings to the roots of younger kin ‘receiver’ seedlings than to stranger ‘receiver’ seedlings, suggesting a fitness advantage to genetically related neighbours (Pickles et al. unpubl.). ... An additional selection process could be as simple as spatial proximity. Daughter trees are more likely to germinate close to their mother, and the mycorrhizal network can be expected to conserve energy by transporting nutrients no farther than needed. Besides that, there's other evidence of kin selection in plants, in the form of reduced root competition. http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12121/pdf http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12121/p... But there's a broader point here. You're reading the word "mothering" narrowly, only w/r/t/ the selection of individual organisms. But selection can also take place on the whole plant community. Eugene Odum, widely considered the father of ecology, points this out: https://www.youtube.com/watch?v=6P9V6h2z79w&t=3m15s https://www.youtube.com/watch?v=6P9V6h2z79w&t=3m15s Plants can't get up and walk away, and polyculture plant communities are healthier than monocultures. So I would argue that even in the hypothetical absence of kin selection, "mothering" could take the form of encouraging a diversity of species in a tree's immediate surroundings, making a favorable local environment for their offspring.

dmix 9y ago

This was the specific quote from the article: > In later experiments, we’ve been pursuing whether these older trees can recognize kin, whether the seedling that are regenerating around them are of the same kin, whether they’re offspring or not, and whether they can favor those seedlings — and we found that they can. That’s how we came up with the term “mother tree,” because they’re the biggest, oldest trees, and we know that they can nurture their own kin. It seems that Kevin Beiler was the one who did research about this so that may be a good place to start rather than the author. But whenever reading something like this quote below, where it's clearly a useful narrative for funding and public support, I find it's always good to be skeptical about how far that analogy extends: > We’ve got a lot of interest from First Nations groups in British Columbia because this idea of mother trees and the nurturing of new generations very much fits with First Nations’ world view.

schiffern 9y ago

These networks also transport signalling and defense molecules, which seem to transmit kin selection information. They also (as you might expect) work better on plants of the same species. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4497361/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4497361/ >The relatedness of neighbours in mono-specific plant communities can also influence whether MNs will elicit adaptive behavioural changes. For example, foliar nutrition in AMF Ambrosia artisifolia L. improved when it was integrated into an MN with related plants but not conspecific strangers (File et al. 2012). Likewise, in mono-specific pairs of EMF interior Douglas-fir grown in greenhouse conditions, foliar micronutrients were increased in kin compared with strangers grown with older conspecifics (Asay 2013). This appears to be linked with mycorrhizal association of this system as mycorrhizal colonization was also elevated in kin seedlings (File et al. 2012; Asay 2013). These findings reveal that MNs can play an integral role in kin selection, but the exact mechanisms by which they do this are unclear. However, there is strong evidence that biochemical signals derived from mycorrhizas or roots are involved. For example, Semchenko et al. (2014) showed that root exudates carried specific information about the genetic relatedness, population origin and species identity of neighbours, and locally applied exudates triggered different root behaviour responses of neighbours. This included increased root density, achieved through changes in morphology rather than biomass allocation, suggesting the plants limited the energetic cost of their behaviour. >Because the overwhelming majority of plants are predominantly mycorrhizal in situ, any root exudates involved in kin recognition are likely to be filtered through mycorrhizal fungi. In a recent study using stable-isotope probing, we found that MNs transmitted more carbon from older ‘donor’ Douglas-fir seedlings to the roots of younger kin ‘receiver’ seedlings than to stranger ‘receiver’ seedlings, suggesting a fitness advantage to genetically related neighbours (Pickles et al. unpubl.). ... An additional selection process could be as simple as spatial proximity. Daughter trees are more likely to germinate close to their mother, and the mycorrhizal network can be expected to conserve energy by transporting nutrients no farther than needed. Besides that, there's other evidence of kin selection in plants, in the form of reduced root competition. http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12121/pdf http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12121/p... But there's a broader point here. You're reading the word "mothering" narrowly, only w/r/t/ the selection of individual organisms. But selection can also take place on the whole plant community. Eugene Odum, widely considered the father of ecology, points this out: https://www.youtube.com/watch?v=6P9V6h2z79w&t=3m15s https://www.youtube.com/watch?v=6P9V6h2z79w&t=3m15s Plants can't get up and walk away, and polyculture plant communities are healthier than monocultures. So I would argue that even in the hypothetical absence of kin selection, "mothering" could take the form of encouraging a diversity of species in a tree's immediate surroundings, making a favorable local environment for their offspring.