Now there's a math problem -- What densities and arrangements of spore distribution would require 40 sexes, 400, or 4000 to create a sufficient level of genetic mixing over the long run?

Does it mean that my yard is so full of fungus spores of all different kinds of fungi, that they have to be able to sort themselves out? I was amazed this fall to see a new mushroom in my yard, the Shaggy Parasol - in 4 widely-spaced locations across my 1.3 acres. Their spores must have been everywhere across the landscape at one time.