关键词: 洲际入侵, 生态位稳定性, 生态位偏移, 物种分布模型

Abstract

Biological invasions represent a growing threat to biodiversity. The movement of organisms among continents by humans has caused profound changes in structure and function of the ecosystem to which they have been introduced. By testing the differences in the relative contributions of the various origins of the invasive plants to each region, we found intercontinental invasions were more prevalent than intracontinental invasions, primarily including the exchange of species among Eastern Asia-North America, Eastern Asia-South America, Europe-South Africa, Europe-North America, Europe-Eastern Asia, and North America-Oceania. They have posed a higher threat than intracontinental invasions. Thus, preventing future invasions is the most cost-effective form of management. Species distribution models (SDMs) are increasingly used to estimate risks of biological invasions. Niche stasis, the tendency of a species niche to remain unchanged across space and time, is often assumed when applying these models to predict and explain biogeographical patterns. Yet, both niche change and conservatism have occurred for intercontinental invasive exotic plants, which were severely disconnected from their source populations and often adapt rapidly to conditions in the new range. To further understand the niche characteristics of invasive species, it is therefore necessary to consider which factors limit range expansion in the native region. After comparing the similarities and differences of invasive species expansion across continents to within continents, we propose that the probabilities of niche shifts occurring depended primarily on the ecological and evolutionary processes limiting the species in its native range such as dispersal limit, species interaction, adapted evolution, ecological plasticity and population characteristics. Most limited factors of species niche properties are more consistent with there being a niche shift than niche stasis in the new range. Therefore, we suggest the following areas for future research: (1) multi-scales studies on niche attributes across spatial, temporal, environmental and phylogenetic investigations; (2) comparative studies that identify both the groups of species that are characterized by environmental niche stasis or shifts, and the traits that the species are more prone to niche change; and (3) niche dynamics over time to estimate the propensity, historical rate, and magnitude of niche shift. Such understanding will improve our confidence in SDM-based predictions of the impacts of climate change and species invasions on species distributions and biodiversity.

Key words: intercontinental invasion, niche stasis, niche shift, species distribution model