DOI: 10.5061/dryad.6t1g1jxbq
title: Data from: Climatic niche shift by the introduced non-native species <em>Sciurus carolinensis</em>

description: We aimed to test the hypothesis of bioclimatic niche conservation in an
 alien species. The study location was the Northern Hemisphere temperate
 and boreal zones. We studied tree squirrels of the genera Sciurus and
 Tamiasciurus, especially S. carolinensis (Eastern Grey Squirrel). Climatic
 response surface species distribution models (SDMs) are fitted using a
 limited set of biologically-relevant bioclimatic variables. Two models are
 fitted for Sciurus carolinensis: one for its North American distribution
 alone, and the second for this plus its naturalised European distribution.
 Each model is used to simulate the species’ potential global distribution.
 Models are fitted also for S. vulgaris (Eurasian Red Squirrel), 12 further
 North American, and two further Eurasian tree squirrels. The realised
 bioclimatic niches of S. carolinensis, two species with which its North
 American distribution overlaps, and S. vulgaris are compared graphically.
 All the SDMs fitted gave excellent goodness-of-fit values. The two SDMs
 fitted for S. carolinensis simulate markedly different potential
 distributions, notably in Europe. The model fitted to the North American
 distribution alone simulates high suitability from France eastwards to
 Ukraine and onwards to Central Asia, but absence from the British Isles.
 That fitted including the naturalised European distribution, in contrast,
 simulates high suitability in the British Isles and only sparse areas of
 low suitability elsewhere across Europe from Spain to Ukraine and Russia.
 The latter model also simulates areas of high suitability in Pacific
 North-west North America and Chile. Graphical exploration of the realised
 bioclimatic niche of S. carolinensis showed the thermal niche occupied in
 Europe to have no overlap with that occupied in North America. The
 bioclimatic realised niche of S. carolinensis in Europe was not predicted
 by an SDM fitted to its North American distribution. Such lack of niche
 conservatism has important implications for the use of SDMs in screening
 potential alien introductions and in planning conservation translocations.
description: # Data from: Climatic niche shift by the introduced non-native species
 *Sciurus carolinensis* Dataset DOI:
 [10.5061/dryad.6t1g1jxbq](10.5061/dryad.6t1g1jxbq) ## Description of the
 data and file structure Modelling the distributions of *Sciurus
 carolinensis* and related North American and Eurasian temperate and boreal
 tree squirrels as part of an investigation of the potential climatic niche
 shift by this species in its naturalised European range. ### Files and
 variables #### File: Eurasian_squirrels.nam **Description:** see
 README_First__Description_of_deposited_files.pdf #### File:
 Eurasian_squirrels.asc **Description:** see
 README_First__Description_of_deposited_files.pdf #### File:
 README_First__Description_of_deposited_files.pdf **Description:**
 Description of the organisation and content of the deposited files ####
 File: Sciurus_carolinensis.nam **Description:** see
 README_First__Description_of_deposited_files.pdf #### File:
 Tamiasciurus_plus_Sciurus.nam **Description:** see
 README_First__Description_of_deposited_files.pdf #### File:
 Sciurus_carolinensis.asc **Description:** see
 README_First__Description_of_deposited_files.pdf #### File:
 Tamiasciurus_plus_Sciurus.asc **Description:** see
 README_First__Description_of_deposited_files.pdf #### File:
 CRU_biocli_global_61-90 **Description:** see
 README_First__Description_of_deposited_files.pdf ## Code/software All
 files are 'flat ASCII' files and can be viewed with any text
 editor.