Global heterogeneity of latitudinal patterns in herbivory between native and exotic plants

Abstract

Latitudinal gradient of herbivory that differs between native and exotic plants has been an open issue. It is expected that a latitudinal gradient of herbivory will be evident for native plants; this gradient in exotic plants may lag behind native plants in terms of co-evolution with local abiotic and biotic factors in introduced area. Our study aims to elucidate the difference in latitudinal gradient of herbivory between native and exotic plants globally, while exploring the underlying mechanisms driving the latitudinal gradient of herbivory with biotic and abiotic factors. To achieve this, we analyzed herbivory data from 94 studies and calculated 862 herbivory effect sizes (zr) to quantitatively characterize the intensity of latitudinal herbivory gradient. For each herbivory data, we matched the corresponding plant identity (native/exotic), herbivore feeding guilds and climate data to reveal the contribution of these factors to zr. Our findings demonstrate a significant decrease in the latitudinal gradients of with increasing latitude for native plants, a pattern not observed for exotic plants. The heterogeneity in latitudinal gradients of herbivory between native and exotic plants is mediated by herbivore feeding guilds. There is a significant influence of climatic factors on the latitudinal gradient of herbivory for native plants, but not for exotic plants. Overall, our results underscore a general heterogeneity in global macroecological herbivory patterns between native and exotic plants, and highlight the role of biotic and abiotic factors in explaining these global-scale differences.