Cosmopolitan species - who spread them?

[ian]

I've just realised I'm really lax at coming on the forum at the moment - I usually do my social stuff on commute so I'm massively out of sync.

Looking at Sarah Lloyd's amazing photos ( https://sarahlloydmyxos.wordpress.com/ ) I see some familiar species names - I have Arcyria denudata and Badhamia utricularis from my own garden ( and now in cultivation ) yet we're literally the opposite sides of the planet. If these were plants or animals that would point to human activity. 

Are these things ancient and unchanging ( you'd expect them to have speciated )? Or have they arrived in soil and plants brought by humans, how could we tell? And what might they have displaced on introduction. Or.. are their spores light enough that they could spread globally by themselves? 

[RyChu]

In one species of mushroom, Schizophyllum commune, research was carried out, by Raper, et al (1958) that genetically demonstrated that this dispersal mechanism has led to a world-wide distribution of this species. - http://www.botany.hawaii.edu/faculty/wong/BOT135/Lect05_c.htm

Could be light enough

[RyChu]

Human activity seems very likely though, spores are small and have a good storage time

[Kenneth Ramos]

I would venture a guess that human activity, insects, wind, and wildlife all play a role in the dispersal of slime molds.  As for displacement of other organisms, I really haven't given much thought too but it could be possible I suppose.  As for myself, I think that all biotic and abiotic things have purpose but as for acellular and cellular slime molds, there has to be more to or for them than just their reproductive life cycle, somewhere along the line they must contribute to the environment in some form or fashion other than to provide people like us with a curiosity to be scratching our heads over.  I read somewhere, way back in the day, where through the use of bio-mathematics some cellular slime molds have made significant contributions to certain computer programs.