There likely could be other benefits to them sharing such as:
when there is more than they can use, particularly that the mushroom does not like in their environment
producing more leaves is likely highly beneficial for the mushroom, for shade both living and fallen, nutrients and cover with fallen leaves.
Similar for the tree, but also mushrooms are recycling minerals from dead material.
I don't know if there'd be "stingy" trees (aside from vastly different nutrient needs), I could see it more of miscommunication or having too much difference with language/biologic pathways. EDIT: Also I gotta imagine that giant trees don't even bother counting it for mushrooms so long as they aren't stressed. Sugar water is in the grid, take as much as you want.
Trees that rely on myco networks usually only get giant because of previous myco networking bonds, which funnel excess nutrients between not just the fungi but also other trees within the system. And depending on the involved species, this sometimes includes multiple plant species exchanging nutrients.
Friendly reminder that cooperation is mutually beneficial and the mathematical solution to the prisoner's dilemma is to cooperate but not be a pushover.
The mathematical solution to the prisoners dilemma depends on how the variables are framed. The standard values are chosen to represent your point and so don't provide evidence of anything.
In the sense of the values awarded for cooperation vs competition? Sure it's an approximation but that doesn't mean it's arbitrary. The entire point is to explore the nature of altruistic behavior, which we know exists. We know there are deer who groom each other even though it is in each deer's best interest to be groomed but not groom in turn. There is a larger benefit to betrayal than to cooperation but a cost associated with everyone acting selfishly.
The prisoner's dilemma is a model of reality. Sure you can insert numbers that make it work in reverse but it's as valid as saying gravity is 4m/s² proves that I won't die by jumping off this building.
What? The first picture in the article is a mycorrhizal mushroom (the fly agaric). If you mean edible fungi, then all of the members of the boletus family (which includes porcini) are mycorrhizal.
"Darwin's theory of evolution by natural selection is entirely focused on an explanation of life's biological diversity. It is a scientific theory meant to explain observations about species. Yet some have used the theory to justify a particular view of human social, political, or economic conditions. All such ideas have one fundamental flaw: They use a purely scientific theory for a completely unscientific purpose. In doing so they misrepresent and misappropriate Darwin's original ideas"
I think the post is pointing out that nature doesn't work the way social darwinists think it does. Although symbiosis between different species, as shown here, isn't the strongest argument they could have chosen. Personally I would have gone with (non-kin) altruism.
I don't see why social darwinists wouldn't like it. I mean, that fungus is thriving. Thus, it must be a really strong individual who made good decisions (associating with trees when it was advantageous).
Isn't survival the single biggest trade incentive though? Like, I go to work everyday so I can buy food, but not because it's so yummy in my tummy, I do it because I'll die if I don't.