All the bio books I ever read said it was mice: Birds eat the fruit but don't digest the seeds, mice digest everything; only mice are bothered by the capsaicin. But fungus? Now, that's new to me, and pretty cool.
That Smithsonian article is a well-written and fun read, thanks! I might try planting some chilis in my apartment garden this summer.
SeeHear also: New research indicates chili pepper plants may have developed their signature heat as a way to fight off fungal infections caused by insects. - Talk of the Nation, August 15, 2008