User:Amariotti.23/sandbox

This is my new sandbox for Wikipedia.

Addition with Citation: It is hypothesized that fungi have evolved to make themselves more attractive to ant species through the development of enzymes that allow the ants to access nutrition in the fungal mass.

3 Suggestions: I have 3 suggestions to improve this page: 1) More could be added about the importance of partner fidelity between the species and how infidelity is detrimental. Especially as it pertains to the secondary symbionts.

2) There could be a section that speaks to the convergent evolution among species. It is true the attines are the major species of ant that partakes in such symbiosis but many species of ant that also partake in this symbiosis have evolved to develop similar traits and habits.

3) More could be added about the medical significance of the coevolution of antibiotic producing bacteria that fight the parasitic escovopsis.

My contribution to Wikipedia can be found on the page titled Ant-Fungus Mutualism and is below as well

Partner Fidelity
Partner fidelity can be witnessed through vertical gene transmission of fungi when a new colony is begun. First, the queen must mate with several males to inseminate her many eggs before she flies off to a different location to begin a new colony. As she leaves, she takes with her a cluster of mycelium (the vegetative portion of the fungus) and actually begins a new fungal garden at her resting point using this mycelium. This grows to become the new fungal farm complete with the genes of the original cultivar preserved for another generation of ants. The relationship between Attine ants and the Lepiotaceae fungus is so specialized that in many cases the Lepiotaceae is not even found outside of ant colony nests. It is clear that evolutionary pressure has been exerted on these ants to develop such an organized system in which to feed the fungus and continue its reproduction.

Studies done (with the concept of the Prisoner's Dilemma in mind) to test what further drives partner fidelity among species have shown that external factors are an even greater driving force. The effects of cheating ants (ants who did not bring plant biomass for fungal food) had a much smaller effect on the fitness of the relationship than when the fungi cheated by not providing gonglydia. Both effects were exacerbated in the presence of infection by escovopsis, resulting in close to a 50% loss in fungal biomass. It is clear that the risk of infection from parasites is a driving external factor in keeping these two species loyal to one and other. Though external factors play a large role in maintaining fidelity between the mutualists, genetic evidence of vertical transmission of partner fidelity has been found among asexual, fungus cultivating ant species. Factors such as vertical transmission do not play as strong a role as environmental factors in maintaining fidelity, as cultivar switching among ant species is not a highly uncommon practice.

My Full Paper
Ecosystems are the highest level of biological organization: compilations of interacting communities of organisms. Living in an ecosystem requires a large amount of contact between various different species. In many instances, highly specialized relationships between organisms, known as symbiosis, develop over millennia of sharing space and fighting to survive. Often when one thinks of a symbiotic relationship they consider mutualism, an affiliation named for the fact that both partners benefit equally from the help of the other. Some ants, most notably those of the genus Atta (known as the Attines) form complex relationships with fungi in which they collect food for the fungi and in return the fungi provide energy rich globules for the insects to feed on. From the nature of coevolution across different ant species, to the external effects exerted by entities outside of the two aforementioned players, the mutualistic relationship between ants and their fungal partners has become highly specialized over centuries of coevolution.

While there are many genera of ant that cultivate fungus for food, the most commonly recognized are those of the Atta genus. Famous for the manner in which they collect and carry leaves many times their size back to their colonies, the Attas, are also known as the leafcutter ants. The early ancestors of the Attas began as hunter-gatherers and slowly started to cultivate fungus 45-65 million years ago (Mueller et al., 2001) making them a likely candidate for the title of first farmers on earth. Throughout the course of time, both ant and fungal species have heavily influenced each other’s morphological adaptations in a phenomenon known as coevolution. The ant colonies function within a caste system, in which there are four distinct classes of ant. First are the Minims who farm the fungus and the Minors who protect the foraging lines as the Mediae, the foragers of the colony, gather the plant biomass. Finally there are the Majors who protect the ant colony and clear debris from the path of the foraging lines.

To display just how tightly interwoven the relationship between these organisms is, partner fidelity can be witnessed through vertical gene transmission of fungi when a new colony is begun (Mikheyev et al., 2006). First, the queen must mate with several males to inseminate her many eggs before she flies off to a different location to begin a new colony. As she leaves, she takes with her a cluster of mycelium (the vegetative portion of the fungus) and actually begins a new fungal garden at her resting point using this mycelium. This grows to become the new fungal farm complete with the genes of the original cultivar preserved for another generation of ants. The relationship between Attine ants and the Lepiotaceae fungus is so specialized that in many cases the Lepiotaceae is not even found outside of ant colony nests. It is clear that evolutionary pressure has been exerted on these ants to develop such an organized system in which to feed the fungus and continue its reproduction.

So far we have seen how ants have adapted to best cultivate the fungus, but this relationship is not based solely on the ants with no adaptation seen in the fungi. On the contrary, it is believed that the fungus may have actually initiated this symbiotic relationship by making themselves more attractive to the ants at no personal cost themselves in the process. In the long run, the fungus reaps a larger benefit via the protection and source of food provided by the ants, than the ants do from just having a common food source. Due to the inherent benefits gained from partnering with the ant species, it is easy to see how they may have developed strategies to lure ants into this relationship. It is hypothesized that the development of gonglydia played a major role in the recruitment of ant species (Lange and Grell, 2014). Gonglydia are protein and enzyme rich structures produced by the fungi that are eaten by the ants for sustenance.

It has been discovered that fungi have evolved to produce a myriad of enzymes that breakdown plant biomass and allow them to convert the energy to the production of gonglydia (Lange and Grell, 2014). The gonglydia are mutually beneficial to both partners in that they are easily taken with no cost to the fungi yet provide a quick and full source of protein for the ants of the Attine colonies. Without the gonglydia, it is hard to imagine why the Attas would have any interest in cultivating the fungal species. Based on this evidence it is entirely possible that these fungi evolved to attract ant species for their protection as well as for food. A likely scenario is that these two species survived in close quarters over such a long period of time that their coevolution eventually became a symbiotic relationship.

Further support for the theory that living in close proximity has evolved a mechanism for coevolution over time, is the evidence provided by the convergent evolution of ant and fungal species across a wide geographical range. Convergent evolution is defined as the process in which organisms that are not monophyletic (closely related) or come from different ancestors still develop similar traits to each other. When comparing the ant species A. pilosum with A. cephalotes (attine), the nature of their relationship with their respective fungal cultivars is largely similar, which stands to reason as both ants are of the subfamily Myrmicinae. The differences between species become noticeable when looking at the different types of fungal mushroom cultivated by each. Fungi of the family Lepiotaceae, a commonly cultivated species by Attines, differs greatly from the Pterula species which is cultivated by A. pilosum. Both have an independent origin and their closest level of shared hierarchy is the order Agaricales, yet we see strong similarities between the two species and the manner in which they interact with their ant partners (Munkacsi et al., 2004). Despite their genetic differences, both have developed gonglydial structures to recruit ants as cultivators. The A. pilosum ants have learned through their separate coevolution that the Pterula fungi subsist largely from wood detritus and have thus evolved to gather wood biomass instead of the leaves collected by the Attines.

While the ant and fungal species are the key members of this particular symbiotic relationship, there are two other major players that drive their mutualistic relationship: the bacteria Pseudonocardia and the parasite Escovopsis. The Escovopsis parasite is a mold that grows on the Atta’s fungal partner, choking out the fungus’ ability to survive and produce gonglydia. In response, the ants have developed a secondary mutualist relationship with the bacteria Pseudonocardia. These bacteria live in small pockets underneath the exoskeleton of the ants called the cuticle. What is so incredible about these bacteria is their ability to produce antibiotic factors, which repel the parasitic Escovopsis. Over many millennia, the ants have evolved extremely intricate cuticular crypts in which to house the bacteria. Adaptations in their morphology have allowed specialized structures such as exocrine glands to develop in order to better support the fungal-saving bacteria (Currie et al., 2006) The role played by the bacteria within this relationship is key to the survival of both ant and fungi species.

To understand just how intricate the relationship between these four species are, it is necessary to understand the prisoner’s dilemma. The prisoner’s dilemma is a branch from the school of thought pertaining to game theory. The scenario breaks down as such: if two people are caught in a crime they each have three choices that will give three separate outcomes. They can choose to remain loyal to each other meaning both keep quiet and each serve a two-year sentence. Both can choose to rat each other out (also known as cheating) and each serve a four-year sentence, or one can remain silent while the other cheats resulting in freedom for the cheater and a six-year sentence for the other.

Studies done to test this relationship have shown that the effects of cheating ants (ants who did not bring plant biomass for fungal food) had a much smaller effect on the fitness of the relationship than when the fungi cheated by not providing gonglydia. Both effects were exacerbated in the presence of infection by escovopsis, resulting in close to a 50% loss in fungal biomass (Little and Currie, 2009). It is clear that the risk of infection from parasites is a driving external factor in keeping these two species loyal to one and other. Though external factors play a large role in maintaining fidelity between the mutualists, genetic evidence of vertical transmission of partner fidelity has been found among asexual, fungus cultivating ant species (Kellner et al., 2013). Factors such as vertical transmission (discussed earlier in relation to the queen forming new colonies) do not play as strong a role as environmental factors in maintaining fidelity, as cultivar switching among ant species is not a highly uncommon practice (Mikheyev et al., 2006).

The implications of this battle between bacteria and parasite species to the medical world are astronomical. The “Red Queen Hypothesis” states that all organisms are in an evolutionary arms race with each other, in which each species must evolve new traits and adaptations in order to keep up with each other and survive. The arms race between the parasitic mold and the antibiotic-producing bacteria personifies this perfectly and could lead to novel antibiotics for human use (Barke et al., 2010). Many antifungal and antibiotic drugs have already been discovered using similar means and given the current environment and development of “super bugs” resistant to once powerful antibiotics, these applications could yield important new drugs. The relationship between these many organisms is complex to say the least. From the mutualistic relationship of the ants and fungi to the more intricate levels of symbiosis seen through the interplay of bacterium and molds, there are many players involved. Given so much time to grow and coevolve together, the complexity reflects how closely knit these organisms are and just what can come from the coevolution of species.