What happens to independent candidates under a PR system? Do they just go away?
Depends on the PR system. STV that is used in Ireland (and in Atlasia) and by many on here considered the best election system of all give all the oppertunity to indipendants as well.
Mixed-member as New Zealand and Germany has also leaves it open for indipendant runs.
It's just completly list based PR systems (such as the Swedish one) that make indipendants impossible. But then, on the other hand, when you have five or six viable parties representing different more aspects of the political scale, people who not fit into any party sort of decrease thereby rendering indipendants a bit meaningless.