Incorporating anthropogenic variables into ecological niche modeling to predict areas of invasion of Popillia japonica

Abstract

Niche conservatism providing support for using ecological niche modeling in biological invasions has been widely noticed; nonetheless, the impacts of human disturbance on niche changes and model predictions are not fully recognized. In this study, climate niche changes during the invasion of Japanese beetle (Popillia japonica) were studied under the framework of niche unfilling, stability, and expansion situations. The beetle might undergo niche expansion because of the small native range (Japan) relative to the broad invade range (North America). Relative roles of climatic and anthropogenic factors and their interactions in determining the spread of P. japonica were investigated. Results suggest that the climate niche was conserved during P. japonica invasion, climate niche unfilling rather than niche expansion was observed, suggesting there are suitable climate space remain unoccupied. Inclusion of anthropogenic factors into climate niche model has improved niche model prediction values in areas of high human activity. During P. japonica invasion, anthropogenic factors influenced the climate niche expression and altered the effect of climate suitability. In areas of poor or unsuitable climate, the human activities facilitated the establishment of P. japonica and functioned synergistically, whereas in highly suitable areas, including anthropogenic variables decreased climate suitability. These findings are pivotal to our understanding of climate niche conservatism and niche model transferability when predicting areas of invasion of P. japonica and can be applied elsewhere for predicting other pest’s invasion potential.