Estimating potential global sources and secondary spread of freshwater invasions under historical and future climates

Aim: We employ a climate-matching method to evaluate potential source regions of freshwater invasive species to an introduced region and their potential secondary spread under historical and future climates.
Location: Global source regions, with primary introductions to the Laurentian Great Lakes and secondary introductions throughout North America
Methods: We conducted a climate-match analysis using the CLIMATE algorithm to estimate global source freshwater ecoregions under historical and future climates with an ensemble of general circulation models for climate change scenario SSP5-8.5. Given existing research, we use a climate match of ≥ 71.7% between ecoregions to indicate climatic conditions that will not inhibit the survival of introduced freshwater organisms. Further, we estimate the secondary spread of freshwater invaders to the ecoregions of North America under historical and future climates.
Results: We identified 54 global freshwater ecoregions with a climate match ≥ 71.7% to..., We accessed downscaled historical climate data and climate change projections via the Worldclim database (worldclim.org; Fick and Hijmans 2017). 
Freshwater ecoregion delineations are from Abell et al. (2008).
We used the CLIMATE algorithm (also known as climatch; Pheloung 1996; Crombie et al. 2008) in the provided scripts to model climate match between ecoregions (see article methods for details on which ecoregions)., All scripts are coded in R.

### 研究目的
本研究采用气候匹配方法（climate-matching method），评估淡水入侵物种（freshwater invasive species）向引入区域的潜在源区域，以及历史与未来气候情景下的潜在二次扩散路径。
### 研究区域
全球潜在源区域，其中首次引入区域为圣劳伦斯五大湖（Laurentian Great Lakes），二次引入分布于北美全境。
### 研究方法
本研究使用CLIMATE算法开展气候匹配分析，基于气候变化情景SSP5-8.5下的大气环流模型集合，估算历史与未来气候情景下的全球淡水生态区（freshwater ecoregion）潜在源。结合已有研究，我们将生态区间≥71.7%的气候匹配度作为判定标准，表明该气候条件不会抑制引入淡水生物的存活。此外，我们还估算了历史与未来气候情景下，淡水入侵生物向北美各淡水生态区的二次扩散情况。
本研究通过Worldclim数据库（Worldclim database）（worldclim.org; Fick and Hijmans 2017）获取降尺度历史气候数据与气候变化预估数据。
淡水生态区划数据源自Abell等（2008）的研究。
我们使用配套脚本中的CLIMATE算法（亦称climatch；Pheloung 1996；Crombie et al. 2008），模拟不同淡水生态区间的气候匹配度（具体生态区选取细节参见论文方法部分）。
所有代码脚本均基于R语言编写。
### 研究结果
本研究识别出54个全球淡水生态区，其与原文省略内容的气候匹配度≥71.7%。