fluctuational

FFE systems can produce fluctuational spikes or excursions that might be very large or very small compared to their recent dynamical history, because the quasi-periodicity of the multiple underlying processes can produce random-seeming beats.

Four Hunnnnnn-dred Years « Climate Audit 2006

First we must, as de Vries has shown, distinguish real, genetic, variation from _fluctuational_ variations, due to environmental and other accidents, which cannot be transmitted.

Evolution in Modern Thought Gustav Schwalbe 1880