A simulation study shows impacts of genetic diversity on establishment success of digital invaders in heterogeneous environments

Abstract

We investigated the establishment success of introduced populations from multiple introductions using an individual-based predator-prey ecosystem simulation called EcoSim. The experiment was a simulated reciprocal transplant over two environments (one with homogeneous and abundant resources, one with heterogeneous and fewer resources) with five levels of genetic diversity for inocula, ranging from clonal to the same diversity level as their source population. We tested the hypotheses that increasing genetic diversity of inocula would increase their establishment success, and that this effect would be stronger when inocula were introduced to environments different from that they evolved in. We found that genetic diversity aided in short-term establishment, but only when inocula were introduced to the heterogeneous, low-resource environment. Further, low-diversity inocula sometimes yielded established populations exhibiting greater genetic diversity than high-diversity inocula under the same circumstances (i.e. source and destination environment type). Additionally, we found evidence that the cost of combatting Allee effects via maintaining spatial compactness so as to maintain reproductive success was greater in low-resource environments where intraspecific competition was more intense; this corroborated a mechanical explanation of the evolutionary imbalance hypothesis. Individual-based models have yielded numerous theoretical insights regarding biological invasions, and EcoSim shows promise in producing novel insights in research areas that have proven to be difficult to explore with classical approaches.