Depletion of heterogeneous source species pools predicts future invasion rates

Predicting how increasing rates of global trade will result in new establishments of potentially damaging invasive species is a question of critical importance to the development of national and international policies aimed at minimizing future invasions. Centuries of historical movement and establishment of invading species may have depleted the supply of species available for future invasions, and it has been suggested that the problem of invasions will diminish as a result of this. However, the extent to which source pool depletion affects future invasions remains unclear. Here we describe a mechanistic model that captures the simultaneous effects of depletion of source species pools along with increases in pathway rates (e.g. imports) to predict future numbers of new invasions. We assume that the distribution of species abundance within invasion pathways is positively skewed, which is modelled using a log-normal distribution. Given their high propagule pressure, the most abundant s...预测全球贸易增速将如何催生潜在破坏性入侵物种（invasive species）的新增定植事件，对于制定旨在降低未来生物入侵风险的国家及国际政策而言，是一项至关重要的核心议题。数个世纪以来的历史物种迁移与入侵定植事件，或许已耗尽了可用于未来入侵的物种种源库，因此有观点认为生物入侵问题会因此而趋于缓解。然而，物种种源库枯竭对未来生物入侵的影响程度仍未明确。 本研究构建了一款机理模型，可同时考量物种种源库枯竭与传播路径速率（例如进口规模）提升的双重效应，以此预测未来新增入侵事件的数量。我们假设入侵传播路径内的物种种群丰度分布呈正偏态，并采用对数正态分布（log-normal distribution）对该分布进行建模。鉴于丰度最高的物种拥有极高的繁殖体压力，其...