Mycorrhizal networks and learning

After reading Brian’s post about mycorrhizal networks I went digging around through some older papers and found this, an exploratory piece by my doc student Erin Brewer circa 2003. (Erin was my co-author on the Online Self-Organizing Social Systems paper.) As we examined biological models (like self-organization) to explain what we saw happening in informal online learning communities, mycorrhizal networks caught our attention. I’d forgotten about the topic until recent discussions in the ed tech blogosphere brought it back to memory…

Symbiosis and Learning Communities

Individuals, groups, and communities all form symbiotic relationships for a wide variety of reasons but the underlying impetus is resource sharing. Whether the resource is food, information, or support, individuals come together to share resources (Ribbands, 1953). “Symbiosis is a route by which organisms gain access” to novel resources (Douglass, 1994, p.v), thus allowing an individual access to a resource they would not otherwise have access to (Cooke, 1977).
The ecology of symbiosis provides a useful framework for examining human associations and the ways in which resources, needs, and environments influence associations. Specifically, symbiosis is a useful lens through which group learning can be viewed in order to understand how the environment, individuals, and resources affect a group’s success or failure. Because learning takes place within an environment where learners employ resource sharing in much the same way and for reasons similar to biological symbiosis, it is my hope that a literature review of symbiosis and specifically of three kinds of symbiotic communities will provide insights into how environment, resources, and associations influence a learning community.

First, I will provide a general overview of the traditional taxonomy of symbiosis. This is essential background for the following sections in which I will examine three forms of biological communities: mycorrhizal networks transitory superorganisms, and stable superorganisms. Based upon the review of the literature on symbiosis and these three types of associations, I will conclude with a discussion of important principles of association that can be applied to group learning, and show how each of the three biological systems provide insights into three types of learning groups.

An Overview of Symbiosis

Though the term symbiosis is traditionally used in biology to capture interrelations of species, it can be generalized to apply to any kind of interaction between individuals (individuals being as small as an individual cell or as large as a whole community) (Rayner, 1997; Sapp, 1994). de Bary coined the term symbiosis in a speech given at the German Naturalist and Physicians Association in 1878 (Sapp, 1994). Below is a taxonomy of symbiosis, first posited by Van Beneden in 1873 and latter used by deBary and others (Ahmadjian & Paracer, 1986). Symbiotic relationships are typically categorized as plus, minus, or zero to indicate benefit, harm or a neutral outcome for the individuals involved.

• Parasitism – Plus-Minus: One Individual gains while another forfeits resources. Can be either ectoparasitic (work on the outside of the host) or endoparasitic (work on the inside of the host)
• Commensalisms- Plus-Zero: One individual gains while the host is unaffected
• Mutualism – Plus-Plus: Individuals work together supportively and are interdependent for success (Lembke, 1999).

Parasitism

Parasitism is an association in which one or many individuals benefit at the expense of one or many other individuals. The parasite draws or consumes useful resources away from the host(s) without providing anything in return. It is important to note that the resources that a parasite takes are useful to the host either because the host could have used the resource or because the host could have shared the resource with others in a more mutually beneficial association had the parasite not taken it.

There are a number of different ways of viewing parasitic relationships. Smith and Douglas (1987) break parasitism into two kinds; physiological obligacy, an absolute dependence on a partner, and ecological obligacy, the inability to survive in the natural environment in isolation from the partner. In other words, there are some parasitic relationships that are absolute and others that are dictated by the environment. Cheng (1970) points out that “it is the exceptional parasite that is deleterious,” because when an association begins parasitically, the members of the association tend to negotiate roles until either the associates fail to thrive and thus the association dies, the association ends because a mutually beneficial relationship cannot be attained, or the association changes into a commensalist or mutualist relationship (p.32). As Trager (1970) notes “the most successful parasites are those so well adjusted to their host that they derive food from it without doing it any significant harm” (p.2). Another important aspect of associations is the impact of the association. Often “parasitism is a function of the number of parasites present, i.e., parasite density, rather than an ‘all or none’ phenomenon” (Cheng, 1970, p.32). In other words, the resource draw one individual has on another may be negligible, and only becomes parasitic when to many individuals are drawing resources away without contributing in a meaningful way (Scott, 1969). Warder Allee suggested that parasitic relationships between species are unstable and “tend to disappear and be replaced by cooperation and mutualism” (Sapp, 1994, p.156). Though these descriptions might sounds like double-talk, they are attempting to capture the complexity of parasitism and demonstrate the difficulty in categorizing dynamic relationships. The extent to which a parasite negatively impacts the host is based on multiple factors (Lincicome, 1971), some of which are:

• The length of the relationship – Is the host helping out another who is having a short term resource need, or is there a long term resource draw?
• The evolution of the relationship over time- By providing resources in the short term, can a mutualistic relationship be grown over time (good examples of this are parenting and apprenticeship)? Is the parasitic relationship part of the parasites normal passage into being a more active, contributing member of the ecosystem?
• The environment – Will the environment change in a way that will affect the association in the short term or in the long term?
• Resources created by the association – Are there by-products of the parasitism that provide the host or the community with new/better/more abundant resources? Is the host creating an association that may provide it/him/her with resources sometime in the future?
• Resources lost as a result of the association – Does the host view the loss of resources as a loss? Would the host be better able to use the resources taken by the parasite?
• Other associations within the ecosystem – By supporting a parasite, does the host gain other associations within the ecosystem?
• Attitude – Does the host feel a resource drain due to the way in which it/he/she perceives the association?
• Number of parasites – Can the host maintain normal function with one or a few parasites, and become debilitated only by numerous parasites?

Commensalism

Commensalist relationships are often difficult to identify, being relationships that are somewhere in between parasitic associations and mutualistic associations. As Trager (1970) notes, commensalists are often transitory, on their way to becoming parasitic or more often, mutualist. Commensalism is often explained as “eating from the same table” (Douglas, 1994; Lembke, 1991; Sapp, 1994; Trager, 1970); in other words, ants or rodents that eat the leavings and droppings from a campsite without taking additional resources would be considered commensalist. In this case, the resources the commensalist takes will not be used by the individual providing them, and the commensalist does not provide any resources to the individual in return.

Mutualism

Despite the common misconception that natural systems are based on competition, individualism, and survival of the fittest, mutialism abounds. In fact, Kropotkin (1976) and others show how animals that practice “mutual aid” are fitter than those who are not (Boucher, 1985; Lindauer, 1971; Margulis, 1998; Sapp, 1994; Scott, 1969; Trappe and Luoma, 1995; Van Beneden, 1873; Wakeford, 2001). A.B. Frank suggested, in 1885, that “mycorrhiza are relationships of mutual assistance” (Sapp, 1994, p. 13) where associates actively work together for the benefit of the biological community. Scott (1969) notes that associates form communities because their chance of survival is greatest within such communities.

Mutualistic associations are relationships where members gain a net benefit as a result of the relationship. This benefit is often calculated over time because of the natural ebb and flow of resource sharing over time. The same factors that are considered when determining the extent of a parasitic relationship are also critical in mutualistic relationships.

Mutualistic associations can provide:

• Access to vital resources that would otherwise be in short supply
• Conversion of resources to a usable form
• Redistribution of environmental resources throughout the community
• Nurturing of youngsters by the more established community members
• Thriving of members in conditions in which individuals it could not survive autonomously
• Promotion of coexistence rather than competition
• Resistance to parasites
• Expedition of recycling processes within an ecosystem.

There are many reasons why unions, either intra- or extra- species, are beneficial for the organisms involved. When resources are abundant and easily attainable, there is not an imperative for association. Mutualistic association results from cooperation in resource-limited environments. When organisms form mutualistic associations, however, they alter both the resource needs as well as available resources.

Therefore:

• Their combined resource need is smaller than their cumulative individual resource needs, meaning that as a team they need fewer resources than each would individually
• Redundant functions can be eliminated and specialized functions can be developed
• Different resources can be utilized
• Combined energy can be more efficiently used
• New resources are created

Environment and Community

As it turns out, though deBary broke out three categories of symbiosis, he recognized a continuum of association types and how relationships vary over time (de Bary, 1887; Jeon, 1972, 1987; Jeon & Ahn, 1978; Jeone & Jeon, 1976; Jeon & Lorch, 1967; Price, 1991, 1984, 1980). Wakeford (2001) found that “the terms ‘mutualist’, ‘parasite’, and ‘pathogen’ are fuzzy points on a continuum, along the length of which an association between two organism may fluctuate,” however, they are useful terms in describing associations especially associations that involve a large community (p. 184). Even highly mutualistic communities will have parasitic and commensalist associations.

After deBary’s introduction of the concept of symbiosis, biologists began thinking of parasitism and mutualism as very specific kinds of relationships. The reason biologists had this view was due to the way in which they were carrying out research. When two individual associates are isolated within a lab, they often function in a very predictable manner and neatly fall into one of the three types of associations (Kendrick, 1985, 1991; Lincicome, 1971; Sapp, 1994). As researchers began doing field research, they recognized the wide range of associations that take place as well as the community structure of the associations and the way in which the environment and the resources within an environment influence the community and the associations that form (Agnadhuan & Paracer, 1986; Dayton 1971; Haiston et al, 1960; Jeffrey, 1987; Kanawabe, 1993; Paine, 1966, 1980; Menge & Sutherland, 1976). Because associations occur within a community in an ecosystem, associates’ relationships are dynamic and must be studied in relation to the community rather than as isolated interactions (Carrikk & Wicklow, 1992; Cohen, 1977; Cohen et al. 1990; Davidson et al., 1984; Dethier & Duggins, 1984; Douglas, 1994; Dugan 1986, 1987; Jackson & Mason, 1884; Kawanabe et al, 1993; Kerfoot & Sih, 1987; Patten 1983; Pimm 1982; Pimm & Lawton 1977; Read, 1970; Sapp, 1994; Vandermeer, 1980; Varnam & Hock, 1995; Wakeford, 2001; Werner, 1992; 1978).

The benefits and/or drawbacks associations are based upon multiple factors (Harely & Smith,1983; Kawanabe et al, 1993). As Sapp (1994) relates it was found that “the performance of associations was dependent on environmental factors that operated at any one given moment” (p. 167). Douglas (1994) notes, “many factors, including environmental conditions and developmental age of the organism may influence whether an organism derives benefit or harm from an association” (p. 2). She goes on to explain, “benefit is not an invariant property of an association, but is dependent on the interaction between the association and its environment” (Ibid, p.7). Not only are the interactions between associates of interest, but looking at the environment in which the associations occur is critical in understanding associative relationships.

Three different types of mutualistic communities will be described in detail below: mycorrhizae, transitory superorganisms, and stable superorganisms. By examining how these communities’ function, factors that influence mutualistic associations will be explored and guiding principles of association will be identified. Because any type of group work is symbiotic in the strictly associative sense, looking carefully at mutualistic associations provides a useful lens through which group learning can be viewed.

Mycorrhizae

Mycorrhizae consist of a web of fungus and plants that are linked together to share resources. The fungus acts as a conduit through which resources from plants and soil are transported. This particular biological model is useful to look at in relation to group learning because the mycorrhizae community is based upon community members sharing resources not only within species, but also inter-species in much the same way that a community of practice involves individuals with many different roles.

The energy requirements of the fungus are provided for by the plants it links together. “A single interconnected network of fungus is often shared between several different plants, thus forming a living bridge through which resources may be exchanged from one to the other. The resulting fungus mediated network of different plants is as important for the plants as it is for the fungus” (Wakeford, 2001, p. 44). The network reduces the difference in access to resources between individuals of the same species as well as different species (Kendrick, 1991). It “therefore [reduces] the competitive difference between plants species and promotes coexistence” (Douglas, 1994; p.117).
In Liaisons of Life, Wakeford shows how mychorrhizae are intricate systems whereby members of an ecosystem support each other by providing vital resources to one another, thus challenging the traditional Malthusian belief that natural ecosystems are primarily competitive. Wakeford shows that “interconnectivity can be a strength” rather than a liability (p.15). Trappe and Fogel (1977) suggest that most trees require mycorrhizae to survive. Not only is the community beneficial, but it is necessary for the success of its members. Trappe and Luoma (1995) report that fungal associations help in rehabilitating man-caused disturbances.

Wakeford discusses a number of different ways by which micorrhizal networks benefit the community. First, “micorrhizal networks give plants new ways of obtaining access to key nutrients that would otherwise be in short supply” (p.42). The fungus is able to do this because of its ability to explore the soil while being fueled by the plants it helps to support (Kendrick & Berch, 1985). The fungus is able to forage in a way that would be risky, uneconomical, and in some cases, impossible, for each individual plant to do.

Because mychorrhiza connects a multitude of species, resources accessible to one species but not needed by that particular species can be redistributed via the fungal network to a species that needs the resource but does not have access to it. In so doing, the network supports the community as a whole rather than just one species and acts to redistribute environmental resources throughout the community.

In addition, the mychorrhiza connect young species that are not yet vigorous enough to contribute resources to the community. “Shaded plants, many of which are young seedlings struggling for light, are subsidized by those already bathed in sunshine at the forest canopy. There seems to be an equalization process going on underground. Supplies are shared both within and among species: to those without shall be given, and those with plenty shall have it taken away” (Wakeford, 2001, p. 49). This nurturing of young by the more established community members helps the community to thrive over time by creating a “social security system” for the community members connected to the web. Mycorrhiza plants grow faster than counterparts of the same species that are not linked (Frank, 1894). Read et. al. (1985) suggest that one of the most important aspects of mycorrhizal networks is the nurturing of burgeoning plants by mature plants. By scaffolding young plants the association insures not only continued contribution to the system when the plants mature, but also bio diversity (Kanawabe, 1986, 1987, 1993, Miller & Allen, 1992).

Because of the benefits derived by mycorrhizal associations, “over 90 percent of plants have domesticated their own species of fungus” (Wakeford, 2001, p. 43). And often, a single plant is connected to more than one fungal system, thus acting as a boundary member to various communities. In this capacity, the plant not only shares resources within one community, but acts as a bridge between multiple communities, thus increasing the resources available to each community and its members. Douglas (1994) notes that one advantage of the mycorrhizal web, “to the plant is particularly evident on nutrient poor substrata” because it allows the plant to thrive in conditions in which it could not survive if it were autonomous (p. 5). By reducing the competitive difference by equalizing access to resources, the mychorrhizal fungus promotes coexistence among species rather than competition.

Michael Allen (1991) found “the most important feature of the association appears to be the ability of the extramatrical hyphae to take up and transport resources to the plant from the soil outside depletion zones created by the root itself (p. 9).” In other words, as the plants own root system saps the surrounding soil of needed resources, the fungus acts as an extended root system. In addition to acting as a vicarious root system, the fungus can do something the plant’s root system cannot; break down organic material to release needed resources. It therefore not only extends the plant’s reach, but also expedites the natural recycling processes within an ecosystem (Allen, 1991). The fungus can also convert resources acquired from one plant into forms more usable by other plants, indicating that it has some kind of awareness of each plant’s individual needs (Allen, 1991). The more able the fungus is able to meet the needs of its associates, the stronger the plants become, thus providing the fungus with more energy.

By changing plants’ ability to access resources, mycorrhizae can alter the operational niche of a plant in two ways, “by making previously unavailable resources available to the plant (adding axes in the niche hyperspace), or by increasing the potential gain of available resources (increasing an axis length or increasing the niche response.” “This gain is due largely to the increase in soil volume explored by the fungus.” (Allen, 1991, p. 49) By creating more stable communities, mycorrhizae increase both within an ecosystem.

Despite the benefits of the mycorrhizal association, not all plants that could be in associations are. Allen explains, “for the mycorrhiza to be economically important, resources must be provided in levels beyond those which might be cheaply provided by other means” (p. 50). The plant must perceive some net economic gain either because the mycorrhizal association can provide resources more easily or provide access to resources that would otherwise be unattainable before it will form an association. For this reason, mychorrhiza webs are much less likely to occur in ecosystems that are resource rich.

Interestingly though, the plant connected to a mycorrhizal network is much more likely to survive over the long haul because of inevitable environmental disruptions that occur. Because of this advantage, the community is more resilient and can endure higher levels of environmental stress, thus communities can continue to exist where non-networked individuals cannot.

There are also cases of seemingly parasitic association within the mycorrhizal community, where a non-contributing individual, often a bird or other ambulatory creature taps into the network and saps resources. Despite the drain on the system, even this seemingly negative association does have value. The pilferer transports fungal spores, thereby aiding in distribution of mycorrhizal fungus. This process is especially valuable in areas that have new growth potential, such as occurs following a volcanic eruption (Rayner, 1997).

The mycorrhizal association is clearly mutualistic and iterative; the more the plants provide for the fungus, the more the fungus can provide in return.

Superorganisms

Superorganisms are defined as “a collection of single creatures that together possess the functional organization implicit in the formal definition of organism” (Moritz, 1992, p. 4). “Superorganisms need a sufficient membership so that the number of organisms involved in a task rather than the individual quality of how a task is performed becomes important” (Moritz, 1992 p.5). Working together, cells become colonies and colonies become individuals at even higher levels of organization.” Haken (1984) coined the term “synergistics” and showed that it is a function not only of living things, but also of inanimate systems. A superorganism is a group of individuals who aggregate in a way such that they function as a new-higher level organism. These organisms are self-organizing systems where the individual member is more like a cell within a body than an autonomous entity (Brian, 1983). By functioning at a higher level of organization, the superorganism can function in ways that the individual cannot. In both the transitory and stable superorganism, the sum of all the members’ reactions results in what looks like community intelligence. Individuals react to things as individuals, but because of a base set of rules, the cumulative response looks complex. There is not a central command, but rather a set of responses and an intricate network for communication and means to negotiate (Moritz, 1992). The community coherence is a result of self organizing local factors at the individual level that form the global decisions, and parallel and network operations comprise the elements of communication (Crozier & Pamilo ,1996; Moritz & Southwick, 1992; Oster & Wilson, 1978; Wilson, 1990).

Camazine et al. (2001 p. 3) found that the behaviors and structures of superorganisms are “built through the iteration of surprisingly simple behaviors performed by large numbers of individuals that rely only on local information.” The key to superorganisms is that members rely upon local information provided by neighboring members to inform their behavior. Camazine et al. cautions that “sometimes the most important information comes directly from an individual’s neighbors, often its nearest neighbors,” resulting in individuals’ perception of the group’s activity being myopic, dependent upon local information (p. 21). This decentralized architecture means that “individuals in self-organized social groups do not rely on instructions from a well-informer individual (leaders) in the upper echelons of a control hierarchy to know what to do,” but rather “each individual gathers information on its own and decides for itself what to do” (p. 60). This decentralized organization results in what looks like very sophisticated behavior, even though there is no centralized governing system.

The impetus to aggregate and the functions of members upon aggregation seem to be based upon relatively few rules that are negotiated by the community. The rules are intended to produce behaviors that will be in the best interest of the community as well as the individual. Once an individual joins an aggregate, he/she/it sacrifices self-governing in exchange for the benefits derived from being a member of the superorganism community (Haken, 1984; Olive, 1975). There is no recipe, set of directions, or individual governing body within a self-organizing system. The “interactions within self-organized systems are based on both signals and cues” between members often on a very local level, yet like a ripple in a pond, the decisions made at a local level move outward affecting the community as a whole (Camazine et al., 2001, p.21).

Maurer (1999) notes that these biological systems are composed of “sufficiently large numbers of smaller entities they are able to develop stable structures” (p. 22). The cohesion results from either interactions among the individuals within the system, or as a result of constraints within the ecosystem.

Two distinct models of superorganisms exist; transitory aggregation and stable aggregation.

Transitory Superorganisms
Rayner (1997) discusses in depth the process of aggregation and individuation. The slime mold optimizes short-term self-organizing behavior. Each individual amoeba acts completely independently during ideal environmentally-rich conditions. When conditions shift and resources become scarce, the individual cells aggregate, forming a superorganism called a slug (Martin, et al.1983). Though each amoeba has the same functional abilities when independent, when the cells aggregate, they self-organize into specialized functions (Ashworth & Dee, 1975). The cells cooperate, negotiating roles for members as they join the group and after they become part of the whole. For example “the following experiment can be conducted with the hydra [a multi-celled organism]. If the animal is cut through the middle, two new animals form; the one with the head will regenerate its foot, the one with the foot, its head. This shows that identical cells can develop into entirely different organs. They must therefore somehow receive their instructions from the union of cells and learn where they are-at the end which is to be the head or at the other, destined to become the foot. In other words the individual cells must be able to receive information about their location in the union of cells…the cells must be communicating across fairly long distances” (Haken, 1984, p. 102). The cells change roles and functions based on the needs of the system. What the cells end up doing is determined by the order parameter, created on the one hand by the cooperation between the cells, but on the other controlling the sequence of the individual cell processes to ensure the creation of a particular pattern.

As a result of the community structure, the slug is much more hardy than each individual cell is as an amoeba and needs fewer resources as a group than each individual would if functioning autonomously. By combining, the ameba work together, and become mobile allowing them to move from a stressful environment, to a hospitable environment. Once the slug relocates, the slime mold cells individuate, each cell separating from the group and resuming its existence as an individual amoebae (Carmazine et al. 2001).

In some superorganisms, as with the slime mold, members individuate following aggregation. In other cases, an entire system, though made up of individuals, acts as a single organism over the entire life-cycle of the individual. Much like the individuals cells in a body die and are replaced constantly without disruption to the overall workings of the organism, individuals in a stable superorganism are replaced on a regular basis without having a net-impact on the overall group.

The transitory superorganism is the result of homogeneous individuals coming together to solve a common problem. By aggregating and differentiating responsibilities, the resulting superorganism has abilities and functions that no individual member of the community has. Once the problem is solved, the transitory superorganism breaks apart and each member of the community functions as an autonomous individual.

Stable Superorganisms

Beehives, an example of a stable superorganism, derive their nutrient requirements from resources foraged by the bees. The colony has a communal cafeteria in which there is a continuous sharing of the resources gathered by members foraging outside the hive (Heinrich, 1979). The resources are shared when one member makes a need known and another member provides a resource to meet the need or when a member has a good resource and shares it with the group (Moritz, 1992).

Important attributes of the stable superorganism include it being sessile, maintaining intraorganismic homeostasis, and large community membership. The community is confined to a physiographic site where the resources are stored and shared. Though the location of the colony is sessile, the individual members are not; rather their primary actively is foraging for resources to bring back to the community. The communities archive resources such that they can withstand shortages of incoming resources during environmentally stressful periods. By maintaining large membership, homeostasis can be maintained; many thousands of members are typical.

The community design of stable superorganisms is important for members’ survival and well being because of the need for efficient storage of resources, protection of members, communication between members, and control of environmental factors affecting the members (Free, 1977). Inter-community social structure is highly dependent on the availability of resources. “Spacial and temporal distribution of resources influence greatly the group size” because the community will only grow as resources are available to support the members (Moritz, 1992, p.184).
The primary activity of a stable superorganism is acquisition and re-distribution of resources. Camazine et al. (2001) found that the superorganism’s members focus their efforts on high quality resources, and in fact members stand idle rather than gathering mediocre resources.

Through indirect cooperation, the superorganism’s members function as one integrated system, rather than as a group of individuals living together. Haken (1984), has dubbed the study of self-organizing systems “the science of cooperation” and shows how the same principles apply to self-organizing systems across disciplines (p. 17). He suggests that “order parameter is created by the cooperation of the individual parts; conversely the order parameter rules the behavior of the individual parts” (p. 19). Using a variety of examples, Haken shows how systems settle into a self-organizing pattern which initially emerges as a result of a “choice” made by the components in the system, but once the choice is made, the components are then trapped or as he says “enslaved” by the system they have chosen. This kind of behavior can be seen in very small systems, such as the atom as well as huge systems, such as the earth’s climate.

Some of the principles are:

• Coexistence is achieved through either specialization being the only component that can do a very specific activity and relying on very specific resources, or generalization – being able to do a wide variety of activities and utilize a wide variety of resources.
• Minute changes in environmental conditions can produce dramatic changes, often resulting in entirely new states of order.
• Nature lets the individual parts of the growing organism communicate with each other.
• Systems negotiate behavior that reinforces the system good, therefore responses that are good for the system are reinforced and responses that are bad for the system are suppressed.
• Because there are often many solutions to any given problem that are equally good and bad, there is a need for a mechanism to break the perceived symmetry. This is supplied by context, which provides additional information regarding the problem to indicate a solution.
• A system often resolves conflict of individual choice by dictating a solution.
• The greater the individual choice, the greater the conflict. The system determines how much individual choice there is and how much system choice there is.

Mycorrhizae-Communities of Practice

When individuals form and maintain associations over a prolonged period of time they form a community. The resulting community of different individuals is like the mycorrhizal networks if each member shares resources and gains resources but remains a distinct individual within the group.

Resource Use

By changing individuals’ ability to access resources these communities alter the operational niche of members in one of two ways, by making previously unavailable resources available or by increasing the potential gain of available resources. Stable communities, increase both diversity and productivity within an environment.

Individuals must perceive some net economic gain either because the association can provide resources more easily or provide access to resources that would otherwise be unattainable before it will form an association. For this reason this kind of association is much less likely to occur in environments that are resource rich. If individuals have access to everything they need, they are unlikely to form associations; however, a networked individual in a resource neutral environment is much more stable and resilient to disruptions than is an autonomous individual in a resource rich environment.

Principles of Mycorrhizae

• Environment: Environments that provide all the needed resources to each individual do not promote community structures. Environments whereby individuals have access to different resources are more likely to support associations.
• Resources Use: Resources are shared by community members, often nurturing young or new members without the expectation that such members will contribute back to the community until later in their life cycle. Each full standing member in the community actively creates resources or mines resources both for itself and to share with the community.
• Membership: Membership in the community is long term. By actively addressing the needs of the community, each member’s needs are addressed. The more diverse the community, the greater stability it has over the long term.
• Activity: This model promotes community development, where individual members focus on their own activity, but share resources with the community thus providing a stable community structure.

Instance

Lave and Wanger (1990) coined the term Community of Practice to capture the structure of groups that build mutualistic associations over the long term. Each member is engaged in their own activity, however the community also engages in practice. These long-term associations function in much the same way as the ecosystems connected via a fungal network. Each individual functions autonomously, however all members of the community share resources and support each other’s growth. This kind of group structure creates stable groups that allow each individual to succeed better as a result of the group. In addition, this structure allows for the long-term survival of the group because new members are apprenticed into the community.

Transitory Aggregation-Activity Clusters

Slime mould exemplifies a short-term aggregation. Individual cells function autonomously until a problem presents exists that requires the collaborative efforts of multiple individuals. The cells then aggregate, form a temporary structure that allows them to specialize and work together to overcome the problem, and then disband.

By specializing, cells can focus their energy on doing one function rather having to perform all the functions required of an individual. By collaborating, energy previously spent performing redundant functions can be focused into new functions, in the case of the slime mould, locomotion.

Resource Use

Resources affect both the structure and activity of slime mould. It is scarcity of resources in the form of environmental stress that causes cells to aggregate and collaborate. By aggregating the slime mould not only increases its problem solving abilities due to the cells forming specialized systems to perform vital functions, but it also decreases the overall need for resources by reducing boundaries. The cumulative resource needs of the organism are lower than the resource needs of the cells functioning autonomously. In addition, because the organism has specialized functions, it can more fully utilize existing resources. Finally, in many aggregations, new resources are located and created to meet the current and future needs of the group.

The following principles guide this kind of short-term aggregation:

• Environment: To promote aggregation, the environment needs to be resource limited, so that there are not sufficient resources available for each individual member to successfully accomplish a given task or solve a problem.
• Resources Use: Resources are more efficiently utilized by an aggregate that has specialized functions. Resources are often created by the aggregate to accomplish the task or solve the problem.
• Membership: The membership needs to determine what manner of specialized functions the group needs in order to accomplish the task or solve the problem. The specialization is determined by the group based on the needs of the group (Ishikawa et al., 1975). Any member can take on any function, but once that function is acquired, it is maintained for the duration of the aggregation.
• Activity: This model promotes collaboration, specialization, and group problem solving.

Instance

Transitory aggregation occurs when individuals come together to solve a problem. I have used the term “activity cluster” when humans come together in a transitory aggregation because each member must take on a specialized activity within the group. An example of an activity cluster is a hospital where health care providers such as nurses, doctors, and respiratory therapists work. Activity clusters form around a specific activity (healing patient) or to accomplish a specific task (new forms that need to be submitted). Like the slime mould, the environment induces members of an activity cluster to organize and work together by presenting each individual with a common problem. If a problem can be solved by an individual then there is no impetus for clustering so the key to this kind of group is that it requires specialization and a group effort. To promote activity clusters, problems or tasks must be posed that require individuals sharing a common environment to specialize skills and pool resources.
Typically, transitory aggregates utilize existing resources; however, the combined efforts of the group allow resources to be more efficiently obtained and utilized. In addition there are often new resources gathered or created that can be re-used by the individuals that comprise the group at a future time.

Stable Aggregation – OSOSS

When activity clusters grow in size to involve large numbers of members and maintain their association over the long-term, something akin to superorganisms form. These structures involve very large numbers of individuals coming together to share resources to meet both the needs of individuals as well as the community.

Resource Use

A superorganism’s behavior is driven by individual members foraging for resources, the regotiation (Edwards, Walker, Wiley & Allen, In-press) of resources for a given need, and storing resources for future use.

Principles of Stable Superorganisms:

• Environment: A supportive structure to provide a place for members to meet, identify needs, share, and store resources, and communicate is required. This structure needs to be indeterminate, so the group can grow without restriction. To the extent possible, the structure should not prescribe rules either explicitly or implicitly.
• Resources Use: Pre-existing resources are gathered and shared by group members. In addition, resources are often created to meet a specific need of a member.
• Membership: Large numbers of members are needed; however, no special skills or process required. Not all members will participate in resource sharing activities at any given time.
• Activity: The primary activity is regotiation-the negotiation and sharing of needs and pre-existing resources; however, members also socialize and form the rules of the group by their behavior.

Instance

Wiley and Edwards (2001) identified Online Self-Organizing Social Structures (OSOSS) as important means by which large groups of people come together to learn and problem solve in an online environment. These groups are made up of often thousands of members, whose primary activity is regotiation. Because of the nature of online groups, the resources gathered and shared in the regotiation process are provided in a contextualized, reusable, easily accessed form. In addition, archives of the regotiation process itself becomes a potential re-usable resource to meet future needs of members.

General Principles

Both mychorriza and superorganisms are examples of mutualistic association and function as mutualistic communities in nature, promoting the growth and well being of members. Though the resources shared within these associations are sustentative, the principles by which resources are shared within mutalistic communities can be applied to group interactions where learning occurs as a result of resource sharing.

One reason that symbients benefit from an association is due to specialization. By combining efforts, individuals within a group can specialize in a way that they cannot do as individuals. As Sapp notes, “symbiosis is based on a division of labor, exemplified by reciprocal relations between plants and animals” (1994, p. 25). Reinheimer declared that from the moment division of labor set in, cooperation had been essential to the organic world, for it afforded the best available means of preservation and progress (Sapp, 1994). Resource sharing increases both the diversity and productivity of the entire community (Allen, 1991, p. 49). By “working together, cells become colonies and colonies become individuals at even higher levels of organization” (Margulis, 1998, p. 99). The structure of the environment and the population in a given environment play a role in who joins and the overall success of the group (Margulis & Fester, 1991). In addition, individuals with access to a wide variety of resources are less likely to aggregate.

There also has to be a legitimate need for the individuals to aggregate in order for associations to function mutualistically. This is important to bear in mind when designing learning activities involving group work. A legitimate need for group activity is essential for a successful outcome. In addition, they type of role taken on by members of the group must be considered. In transitory superorganisms, individuals specialize in function to solve a problem, whereas in stable superorganisms, members sharing a common environment bring in whatever resources they can find for the benefit of the community as a whole, and mychorzal communities function much like communities of practice where individuals are linked over the long term but remain distinct individuals contributing the resources they have access to and building long-term stability of the community as a whole.

References

Ahmadjian, V. & Paracer, S. (1986). Symbiosis: An Introduction to Biological Associations. Hanover: University Press of New England.

Allen, M. (1991). The Ecology of Mycorrhizae. Cambridge: University Press.

Ashworth, J. and Dee, J. (1975). The Biology of Slime Moulds. Great Britain: Butler and Tanner

Boucher, D. (1985). The Biology of Mutualism. New York: Oxford University Press.

Brian, M. V. (1983). Social Insects: Ecology and Behavior Biology. London: Chapman and Hall.

Carroll, G. & Wicklow, D. (1992). The Fungal Community: Its Organization and Role in the Ecosystem. New York: Marcel Dekker Inc.

Cohen, J. E. (1977) Food webs and the dimentionality of trophic niche space. Proceedings of the National Academy of Sciences USA, 74, 4533-6.

Cohen, J.E., Briand, F., & Newman, C.M. (1990). Community food webs. Berlin: Springer Verlag.

Cooke, R. (1977). The Biology of Symbiosis. London: John Wiley and Sons, London.

Crozier, R. & Pamilo, P. (1996). Evolution of Social Insect Colonies. Oxford: Oxford University Press.

Dayton, P.K. (1971). Competition, disturbance, and community organization: the provision and subsequent utilization of space in a rocky intertidal community. Ecological Monographs, 41, 351-89.

Davidson, D.W., Inouye, R.S. & Brown, J.H. (1984). Granivory in a desert ecosystem: experimental evidence for indirect facilitation of ants by rodents. Ecology, 65, 1780-6.

De Bary, A. (1887). Comparative Morhpology and Biology of the Fungi, Mycetozoa and Bacteria, English translation of 1884 edition. Oxford: Claredon Press.

De Bary, A. (1898). Lectures on Bacteria. Oxford: The Claredon Press, Oxford.

Dethier, M.N., & Duggins, D.O. (1984). An ‘indirect commensalis,’ between marine herbivores and the importance of competitive hierarchies. American Naturalist, 124. 205-19.

Douglas, Angela. (1994). Symbiotic Interactions. Oxford: Oxford University Press.

Dugan, M.L. (1987). Three-way interactions: barnacles, limpets, and algae in a Sonoran Desert rocky intertidal zone. American Naturalist, 127, 292-316.

Dugan, M.L. (1987). Indirect mutualist complementary effects of grazing and predation in a rocky intertidal community. In Predation: direct and indirect impacts on aquatic communities. ed. W.C. Kerfoot and A. Sih, pp. 188-200. Hanover: University Press of New England.

Frank, A. B. (1894). Die Bedeutung der Mykorrhiza-pilze fur die gemeine Kiefer, Forshwiss. Sbl. 16, 1852-1890.

Free, J. (1977). The Social Organization of Honeybees. Southampton: The Camelot Press.

Hairston, N.G., Smith, F.E. & Slodobokin, L.B. (1960). Community structure, population control, and competition. American Naturalist, 94, 421-5.

Haken, H. (19840. The Science of Structure: Synergetics. New York: Prentice Hall.

Harley, J.L & Smith, S.E. (1983). Mycorrhizal Symbiosis. New York: Academic Press.

Heinrich, B. (1979). Bumblebee Economics. Cambridge: Harvard University Press.

Ishikawa, T. , Maruyama, Y., Matsumiya, H. (1975). Growth and Differentiation in Microorganisms. Tokyo: Japan Scientific Societies Press.

Jackson, R. & Mason, P. (1984) Mycorrhiza. Southampton: The Camelot Press Ltd.

Jeon, K. W. (1972). Development of cellular dependence on infective organisims: micrurgical studies in amoebas. Science 1976: 1122-1123.

Jeone, K.W. (1987). Change of cellular “pathogens” into required cell components. In: Lee, J.J., and Fredrick, J.F., eds., Endocytobiology III. New York Academy of Sciences.

Jeon, K.W. & Ahn, T.I. (1978). Temperature sensitivity: A cell character determined by obligate endosybionts in ameboes. Science 202: 635-637.

Jeon, K.W. & Jeon, M.S. (1976). Endosymbiosis in amoebae: Recently established endosymbionts have become required sytoplasmic components. Journal of Cell Physiology 89: 337-344.

Jeffrey, D. (1987). Soil-Plant Relationships. London: Croom Helm.

Jeon, K.W. & Lorch, I.J. (1967). Unusual intra-cellular bacterial infection in large, free living amoebae. Experimental Cell Research 48: 236-240.

Kawanabe, H. (1986) Cooperative study on the ecology of Lake Tanganyika between Japanese and Zairean scientists, with special reference to mutual interactions among fishes. Physiology and Ecology, Japan, 23, 119-28.

Kawanabe, H. (1987). Niche problems in mutualism. Physiology and Ecology Japan, 24, 75-80.

Kawanabe, H., Cohen, J.E., & Iwasaki, K. (1993). Mutualism and Community Organization. Oxford: Oxford Press.

Kendrick, B. & Berch, S.M. (1985). Mycorrhizae: Applications in agriculture and forestry. In: Robinson, C., ed., Comprehensive Biotechnology, volume 3. Pergamon.

Kendrick, B. (1991). Fungal Symbiosis and Evolutionary Innovations. ed. L. Margulis, and R. Fester. Symbiosis as a source of Evolutionary Innovation. Massachusetts: MIT Press.

Kerfoot W.C. & Sih, A. (1987). Predation: direct and indirect impacts on aquatic communities. Hanover: University of New England.

Lave, J., & Wenger, E. (1990). Situated learning: Legitimate peripheral participation. Cambridge, UK: Cambridge University Press.

Lembke, J. (1991). Despicable Species: On Cowbirds, Kudzu, Hornworms, and other Scourges. New York: The Lyons Press.

Lindauer, M. (1971). Communication Among Social Bees. Cambridge: Harvard University Press.

Lincicome, D. (1971). The goodness of parasitism: A new hypothesis. Ed. Cheng, Thomas. Aspects of the Biology of Symbiosis. London: University Park Press.

Margulis, L. (1998). Symbiotic Planet. Amherst: Sciencewriters.

Martin, G, Alexopoulos, C. and Farr, M. (1983). The Genera of Myxomycetes. Iowa City: University of Iowa Press.

Maurer, B. (1999). Untangling Ecological Complexity: The Macroscopic Perspective. Chicago: University of Chicago Press.

Menge, B.A. & Sutherland, J.P. (1976). Species diversity gradients: synthesis of the roles of predation, competition, and temporal heterogeneity. American Naturalist, 100, 65-75.

Moritz, R. & Southwick, E. (1992). Bees as Superorganisms: An Evolutionary Reality. Berlin: Springer-Verlag.

Olive, L. (1975). The Mycetozoans. New York: Academic Press.

Oster G.F. & Wilson, E.O. (1978). Caste and ecology in social insects. New York: Princeton University Press.

Paine, R.T. (1966). Food web complexity and species diversity, American Naturalist, 100, 65-75.

Paine, R.T. (1980). Food-webs: linkage, interaction strength and community infrastructure. Journal of Animal Ecology, 49, 667- 85.

Pimm, S.L. (1982). Food Webs. London: Chapman and Hall.

Pimm, S.L. & Lawton, J.H. (1977). Number of trophic levels in ecological communities. Nature, 268, 329-31.

Pimm, S.L. & Lawton, J.H. (1978). On feeding on more than one trophic level. Nature, 275, 542-4.

Patten, B.C.(1983). On the quantitative dominance of indirect effects in ecosystems. In Analysis of ecological systems; state-of-the-art in ecological modeling, (ed. W.K. Lauenroth, G.V. Skogerboe and M. Flug), pp. 27-37. Elsevier, Amsterdam.

Price, P. (1991).The web of life: Development over 3.8 billion years of trophic relationships. ed. L. Margulis, and R. Fester. Symbiosis as a source of Evolutionary Innovation. Massachusetts: MIT Press.

Price, P. (1980). Evolutionary Biology of Parasites. New York: Princeton University Press.

Price, P. (1984). Insect ecology, second edition. New York:Wiley.

Read, C. P. (1970). Parasitism and Symbiology. New York: The Ronald Press Company.

Ribbands, C.R. (1953). The Behavior and Social Life of Honeybees. London: Bee Research Association Limited.

Sapp, J. (1994). Evolution by Association. New York: Oxford University Press.

Scott, G. (1968). Plant Symbiosis. London: William Clowes and Sons.

Trager, W. (1970). Symbiosis. New York: Van Nostrand Reinhold Company.

Trappe, J.M., & Fogel,R.D. (1977). Ecosystematic functions of mychorrhizae. In The below-Ground Ecosystem: A synthesis of Plant-Associated Processes. Range Sci. Dep. Ser. No. 26, Colorado State University, Fort Collins.

Trappe, J & Luoma, D. (1992). The ties that bind: Fungi in Ecosystems. In The Fungal Community: Its Organization and Role in the Ecosystem. Eds. Carroll, G. and Wicklow, New York: D. Marcel Dekker Inc.

Vandermeer, J.H. (1980). Indirect mutualism: variations on a theme by Stephene Levine. American Naturalist, 116, 441-8.

Varma, A. & Hock, A. (1985). Mycorrhiza: Structure, Function, Molecular Biology and Biotechnology. Berlin: Springer-Verlag.

Wakeford , T. (2001). Liaisons of Life : Liaisons of Life: From Hornworts to Hippos, How the Unassuming Microbe has Driven Evolution. New York: John Wiley & Sons.

Werner, D. (1992). Symbiosis of Plants and Microbes. London: Chapman and Hall.

Wilson, E. (1990). Success and Dominance in Ecosystems: The Case of the Social Insects. Nordbunte : Ecology Institute.