Because the current set of political ideologies, with one exception, is devoted solely to the economic and social benefit of humans, I come here as the self-appointed spokesperson for the non-human organisms that have no voice.
As the mycologist Paul Stamets recently said, if there were a federation of organisms, humans would be voted off the planet. To give that one exceptional ideology a chance to speak for our biological cousins, we need some form of proportional representation.
Some years ago, the Law Commission of Canada came to the same conclusion in their report on electoral options for Canada, specifying mixed member proportional.
By the way, the hypothetical vote by the “United Federation of Organisms” was also for mixed member proportional, as is my personal preference.