Did we miss some evidence of chaos in laboratory insect populations?

Abstract

The collection and documentation of the experimental evidence of chaos in biological populations have always been elusive. We were puzzled by the observation that the most frequently computed demographic parameter for laboratory insect populations, the population intrinsic rate of increase (r m ), seems too small to induce chaotic dynamics. For example, when it is directly utilized as an approximation to the parameter (a) of the one-parameter discrete logistic model, the parameter seems well out of the chaotic range. In a recent reanalysis of our early laboratory demographic data of 1800 Russian wheat aphids (RWA), we discovered that a proper measure unit conversion should be performed to make the link between r m and the discrete logistic model. We think that this conversion issue may have been ignored historically in biological literature since we are not aware of any uses of the r m in the discussion of chaos. It should be noted that r m is different from the r in discrete logistic model (e.g., May in Nature 261:459-467, 1976). Since extensive demographic data purported to estimate r m have been accumulated in literature on population growth, the finding revealed with our RWA experiment data can easily be verified with the published data in literature. We neararbitrarily surveyed 10 studies (containing 37 datasets of r m ) published in the literature and archived in JSTOR or BioOne databases to test the conversion, and the results confirmed our finding. The finding should significantly expand the evidence base of chaos in laboratory populations of insects and possibly microorganisms, too.

A unified survival-analysis approach to insect population development and survival times

“…Due to my pursuing an engineering (CS) career right after the graduation, the dissertation work was not submitted for publication until a decade later when I returned to UI campus to pursue my second PhD in Computer Science (CS). The other publications generated from this dissertation included: Ma and Bechinski (2008a, 2008b, 2009a, 2009b, 2009c, 2009d) and Ma (2010, 2011), all listed in the references section 2 , 14 , 15 , 39 , 43 , 45 – 47 . Further information on my two PhD dissertations can be found at: https://www.mathgenealogy.org/id.php?id=132255 .…”