One Direction Under Many Stressors: A Cross-System Sorting Invariant over Grounded Ecological Standpoints

Abstract

Parallax computes, for co-located species, the divergence between their standpoints at a shared environmental value. This paper reports what appears when six such divergences, computed independently across a European network (dissolved oxygen in an estuary; temperature in four lakes, a sea and a river; drought in a forest; winter ice in a subarctic lake; and a pathogen), are read together rather than one at a time. Each divergence, on its own, is textbook ecology. Swept together, they reveal an invariant: every stressor sorts the co-located community in the same direction, eurytopic generalists in, specialists out, regardless of which stressor and which watershed. The winner guild is disproportionately non-native, and the sharpest divergence is a pathogen the invader carries harmlessly and the native cannot survive: climate stress and biological invasion point the same way. The novelty is not any single divergence but the invariance across five physically distinct events and across watersheds, made visible only because standpoints are computed from sourced physiology and differenced under a commensurability discipline. These are hypotheses at the standpoint level, resting on six systems, not a proof.