Data from: Fish faunal provinces of the conterminous United States of America reflect historical geography and familial composition

Although the conterminous USA has a long history of ichthyological exploration, the description of biogeographical provinces has been ad hoc. In this study we quantitatively determined fish faunal provinces and interpreted them in the context of the geological history of North America. We also evaluated influences of major river basin occupancy and contemporary environmental factors on provincial patterns. Our data set comprised 794 native fishes, which we used to generate a presence and absence matrix for U.S. Geological Survey (USGS) four-digit hydrologic units. Three nested data sets were analysed separately: primary freshwater families, continental freshwater families (including primary and secondary families) and all freshwater families (including primary, secondary and peripheral families). We used clustering analysis to delimit faunal breaks and one-way analysis of similarity (ANOSIM) to determine significance among clusters (i.e. provinces). We used an indicator-species analysis to identify species that contributed most to province delineations and a similarity-percentage (SIMPER) analysis to describe the relative influence of representatives from each category (i.e. primary, secondary, peripheral) on provincial boundaries. Lastly, we used a parsimony redundancy analysis to determine the roles of historical (i.e. major river basin) and contemporary environmental factors in shaping provinces. Analysis of the nested data sets revealed lessening provincial structure with inclusion of more families. There were 10 primary freshwater provinces, 9 continental freshwater provinces and 7 all freshwater provinces. Major basin occupancy, but not contemporary environmental factors, explained substantial variance in faunal similarities among provinces. However, provincial boundaries did not conform strictly to modern river basins, but reflected river-drainage connections of the Quaternary. Provinces represent broad-scale patterns of endemism and provide a starting point for future studies. Relative malleability of province boundaries in the continental interior highlights this region as biogeographically diverse and dynamic. Interior-core provinces of this region (Central Gulf Coastal Plains, Northern Interior) have not been recognized previously and warrant further study.尽管美国本土48州的鱼类学考察（ichthyological exploration）历史悠久，但针对其生物地理分区（biogeographical provinces）的划定始终缺乏系统性框架，多为临时性、非系统性的工作。本研究通过定量方法明确了鱼类动物地理分区（fish faunal provinces），并结合北美地质历史对其进行解读；同时评估了主要流域占据情况与当代环境因子对分区格局的影响。本数据集涵盖794种本土鱼类，以此构建了美国地质调查局（U.S. Geological Survey, USGS）四位数字水文单元（four-digit hydrologic units）的物种有无矩阵（presence and absence matrix）。我们分别分析了三套嵌套数据集：淡水初级科（primary freshwater families）、大陆淡水科（continental freshwater families，包含初级与次级淡水科）以及全淡水科（all freshwater families，包含初级、次级与外围淡水科）。我们采用聚类分析（clustering analysis）划定动物区系分界（faunal breaks），并通过单向相似性分析（one-way analysis of similarity, ANOSIM）确定各聚类组（即分区）间的显著性差异；采用指示物种分析（indicator-species analysis）识别对分区划定贡献最大的物种，并通过相似性百分比分析（similarity-percentage analysis, SIMPER）阐明各类群（即初级、次级、外围类群）对分区边界的相对影响。最后，我们采用简约冗余分析（parsimony redundancy analysis）明确历史因素（即主要流域）与当代环境因子在塑造分区格局中的作用。对嵌套数据集的分析显示，随着纳入的科类增多，分区结构的显著性逐渐降低。本次研究共划定10个淡水初级科分区、9个大陆淡水科分区以及7个全淡水科分区。主要流域占据情况能够解释分区间动物区系相似性的显著差异，而当代环境因子则无此解释效力。不过，分区边界并未严格遵循现代流域界线，而是反映了第四纪（Quaternary）时期的河流连通关系。这些分区代表了大范围的特有性（endemism）格局，可为未来研究提供基础框架。美国内陆地区分区边界的相对可塑性，凸显了该区域在生物地理上的多样性与动态性。该区域的内陆核心分区包括墨西哥湾中部沿海平原（Central Gulf Coastal Plains）与北部内陆区（Northern Interior），此前未被学界识别，有待进一步研究。