DOI: 10.5061/dryad.sn02v6x3n
title: Data from: Drivers of native and non-native freshwater fish richness across North America: Disentangling the roles of environmental, historical and anthropogenic factors

description: Aim: A better understanding of native and non-native species response to
 environmental conditions, historical processes, and human pressures is
 crucial in the face of global environmental changes affecting
 biodiversity. Here, we evaluate the relative roles of environmental,
 historical, and anthropogenic factors in influencing species richness of
 native and non-native freshwater fishes in watersheds across North
 America. Location: North America (exclusive of Mexico) Time period: Recent
 Major taxa studied: Freshwater fishes Methods: We compiled an extensive
 dataset of native and non-native fish richness in 2993 watersheds across
 North America, together with corresponding data for environmental
 (climatic, geographic), historical, and anthropogenic factors. We used
 variance partitioning and hierarchical partitioning to quantify the
 relative importance of environmental, historical and anthropogenic factors
 in explaining richness variation in native and non-native fishes (overall,
 and by geographic origin [foreign/translocated] and pathway
 [authorized/unauthorized]), while accounting for correlations among
 explanatory variables and spatial autocorrelation. Results: Overall
 importance of environmental and anthropogenic factors was greater than
 historical factors in explaining both native and non-native richness.
 Precipitation-related factors were more important in explaining native
 richness, whereas non-native richness was largely associated with
 temperature-related factors. However, richness related to authorized
 introductions was less constrained by temperature than unauthorized
 introductions. Dam density, road density and urbanization gradient were
 major anthropogenic factors related to non-native richness, yet their
 relative importance varied among origin- and pathway-based categories.
 Conclusions: Our findings indicate different environmental drivers
 influence native and non-native fish richness patterns in North America.
 The accumulation of non-native species in watersheds depends on the
 interaction between environmental conditions and anthropogenic-based
 processes related to introduction history including geographic origin,
 introduction pathway, and propagule pressure, where the latter likely
 plays a major role. Warmer regions with high human population densities
 and more impoundments are more prone to fish invasions, mostly via
 unauthorized introductions.
description: <b>Freshwater fishes
 in North America: Species by watershed matrix (non-native species
 undifferentiated)</b> A comma-delimited file that
 contains occurrence data for 949 freshwater fish species in 2993
 watersheds across Canada and United States. Species occurrences are coded
 either as ‘native’ (native to North America, found within the native
 range) or ‘nonnative’ (both foreign species and native transplants),
 whereas ‘0’ indicates absence. See the accompanying metadata document
 (README_NAFWFISHdata.pdf) and the Materials and Methods section of the
 original article for the data sources. sp x watershed_nonnative
 undifferentiated.csv <b>Freshwater fishes in
 North America: Species by watershed matrix (non-native species by
 origin)</b> A comma-delimited file that
 contains occurrence data for 949 freshwater fish species in 2993
 watersheds across Canada and United States. The occurrences of non-native
 species are coded by geographic origin i.e. ‘foreign’ (not native to North
 America) and ‘translocated’ (native to North America, moved beyond of
 native range). The occurrences of species native to North America within
 their native ranges are coded as ‘native’ and species absences are
 indicated by ‘0’. See the accompanying metadata document
 (README_NAFWFISHdata.pdf) and the Materials and Methods section of the
 original article for the data sources. sp x watershed_nonnative by
 origin.csv <b>Freshwater fishes in
 North America: Species by watershed matrix (non-native species by
 pathway)</b> A comma-delimited file that
 contains occurrence data for 949 freshwater fish species in 2993
 watersheds across Canada and United States. The occurrences of non-native
 species are coded by introduction pathway i.e. ‘authorized’ (legally
 sanctioned introductions) and ‘unauthorized’ As a caveat, some species
 known to be introduced through authorized pathways may also have been
 introduced via unauthorized means. The occurrences of species native to
 North America within their native ranges are coded as ‘native’ and species
 absences are indicated by ‘0’. See the accompanying metadata document
 (README_NAFWFISHdata.pdf) and the Materials and Methods section of the
 original article for the data sources. sp x watershed_nonnative by
 pathway.csv <b>Freshwater fishes in
 North America: Species richness by watershed matrix </b>
 A comma-delimited file
 containing richness of native and non-native (overall, and by geographic
 origin [foreign/translocated] and pathway [authorized/unauthorized])
 freshwater fishes in 2993 watersheds across Canada and United States. See
 the accompanying metadata document (README_NAFWFISHdata.pdf) and the
 Materials and Methods section of the original article for the data
 sources. species
 richness x watershed.csv <b>Metadata for data
 files</b> A
 pdf document that contains data sources, and definitions of variable names
 and codes in the comma-delimited data files. README_NAFWFISHdata.pdf