DOI: 10.5061/dryad.mpg4f4r8q
title: The role of climate and species interactions in determining the distribution of two elevationally segregated species of small mammals through time

description: The relative importance of abiotic and biotic factors in determining
 species distributions has long been of interest to ecologists but is often
 difficult to assess due to the lack of spatially and temporally robust
 occurrence records. Furthermore, locating places where potentially highly
 competitive species co-occur may be challenging but would provide critical
 knowledge into the effects of competition on species ranges. We built
 species distribution models for two closely related species of small
 mammals (Neotoma) that are largely parapatric along mountainsides
 throughout the Great Basin Desert, USA using extensive modern occurrence
 records. We hindcasted these models to the mid-Holocene to compare the
 response of each species to dramatic climatic change and used
 paleontological records to validate our models. Model results showed
 species co-occurrence at mid-elevations along select mountain ranges in
 this region. We confirmed our model results with fine-scale field surveys
 in a single mountain range containing one of the most extensive survey
 datasets across an elevational gradient in the Great Basin. We found close
 alignment of realized distributions to the respective abiotic species
 distribution model predictions, despite the presence of the congener,
 indicating that climate may be more influential than competition in
 shaping distribution at the scale of a single mountain range. Our models
 also predict differential species responses to historic climate change,
 leading to a reduced probability of species interactions during warmer and
 dryer climatic conditions. Our results emphasize the utility of examining
 species distributions with regard to both abiotic variables and species
 interactions and at various spatial scales to make inferences about the
 mechanisms underlying distributional limits.
description: Occurrence records for species distribution models came from the
 Global Biodiversity Information Facility (GBIF) (https://www.gbif.org/,
 accessed January 2022) and VertNet (http://vertnet.org/,
 accessed January 2022), and data we collected from surveys throughout the
 Great Basin in the Summer and Fall of 2021. We cropped all records to the
 Great Basin ecoregion, the boundary of which was obtained from the United
 States Geological Survey (USGS) database. We constrained records to dates
 on or after 1950, and with less than or equal to one kilometer coordinate
 uncertainty to reflect the resolution of the data layers. We used the
 spatial analysis georeferencing accuracy (SAGA) protocol to georeference
 data with no recorded coordinate uncertainty (Bloom et al. 2018). We
 thinned locality data to 1km raster cells. From April
 through October 2022, we conducted surveys (24 sites, 6555 trap nights)
 for woodrats in the southern Snake Range of eastern Nevada.
 We also obtained mid-Holocene fossil and midden records assembled
 from the Neotoma Paleoecology Database (http://www.neotoma.db.org; January 2024) (Williams, Grimm et al. 2018), and primary literature (Grayson 1985, Terry et al. 2011) to validate mid-Holocene model projections. We filtered records by excluding records with uncertain identification, restricting to only those with a calibrated median age between 4,500 and 7,500 years before the present and max age &lt;11,700 (Grayson 2011), and trimming all records to our Great Basin extent. All paleontological records included were morphologically identified to species.
description: # **The role of climate and species interactions in determining the
 distribution of two elevationally segregated species of small mammals
 through time**
 [https://doi.org/10.5061/dryad.mpg4f4r8q](https://doi.org/10.5061/dryad.mpg4f4r8q) ## Description of the data and file structure ### Files and variables #### File: Neotoma\_data\_dryad.zip **Description:** Neotomadata.zip file contains 4 .xlsx files that include 2 files (N.cinerea_SDMdata.xlsx, N.lepida_SDMdata.csv) with a total of 547 modern *Neotoma* occurrence records obtained from the Global Biodiversity Information Facility and VertNet database, accessed January 2022, 21 mid-Holocene fossil and midden records (Neotoma_paleodata_cite.xlsx) obtained from the Neotoma Paleoecology Database, accessed January 2024, and 188 *Neotoma* records (SnakeRange_Neotomadata_2022.xlsx) obtained from field surveys of the Snake Range of eastern Nevada, April-Oct 2022. #### Neotoma\_paleodata\_cite.xlsx values are as follows: Species – of the individual, either *N. cinerea* or *N. lepida* url - of the individual record, digital or physical location where the record is stored  #### N.cinerea\_SDMdata.xlsx and N.lepida\_SDMdata.xlsx values are as follows: GUID – global unique identifier for museum specimen data url - of the individual record, digital or physical location where the record is stored lat – of the individual record (WGS 84)  lon – of the individual record (WGS 84) #### SnakeRange\_Neotomadata\_2022.xlsx values are as follows: site# – of the site, a value between 1-24, representing groups of individuals caught in close proximity species – of the individual, either *N. cinerea* or *N. lepida* lat – of the individual record (WGS 84)  lon – of the individual record (WGS 84) ## Code/software Neotoma_modeling.R file contains R language code for ensemble species distribution modeling, including generating model evaluation statistics and response plots, limiting factor analyses, and niche overlap analyses. ## Change log **17 Dec 2024** - One data point from the N.cinerea_SDMdata.xlsx file had the incorrect url link. This is fixed now.