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Keywords:

  • Climate change;
  • ecological niche modelling;
  • Great Basin;
  • insular biogeography;
  • Last Glacial Maximum;
  • montane mammals;
  • North America;
  • species distribution

Abstract

Aim  The goal of this study was to determine the extent of suitable habitats across the basins and ranges of the Great Basin for 13 montane mammals in the present and during the Last Glacial Maximum (LGM). For all these mammal species, we test whether: (1) more suitable habitat was available in basin areas during the LGM; (2) suitable habitat shifted upwards in elevation between the LGM and the present; (3) more ranges have suitable habitat than are currently occupied; and (4) these species are currently restricted to suitable habitats at higher-elevation range areas. We also examine whether and how much distributional response varies among these montane mammal species.

Location  The Great Basin of western North America.

Methods  We re-examine the past and present distributions of 13 Great Basin montane mammals using ecological niche modelling techniques that utilize now widely available species occurrence data and new, fine-scale past climatological GIS layers in the present and at the LGM. These methods provide an objective, repeatable means for visual comparison of past and present modelled distributions for species examined in previous biogeographical studies.

Results  Our results indicate greater areal and lower elevational suitable habitat in the LGM than at present for nearly all montane mammals, and that there is more suitable habitat at present than is currently occupied. Our results also show that lowland areas provide suitable dispersal routes between ranges for most of the montane mammals both at the LGM and at present. However, three of the 13 species have little to no predicted suitable habitat in the LGM near currently occupied ranges, in contrast to the pattern for the other 10. For these species, the model results support more recent long-distance colonization.

Main conclusions  Our finding of suitable lowland dispersal routes in the present for most species supports and greatly extends similar findings from single-species studies. Our results also provide a visually striking confirmation that changes in species distribution and colonization histories of Great Basin montane mammals vary in a fashion related to the tolerances and requirements of each of these species; this has previously been hypothesized but not rigorously tested for multiple montane mammals in the region.