DOI: 10.5061/dryad.dncjsxkvw
title: A tale of four bears: Environmental signal on the phylogeographical patterns within the extant Ursus species

description: Aim: Assessing the relevance of niche evolution in the diversification
 patterns and geographical distribution of species driven by climate
 remains a challenge. We apply an integrative approach to evaluate the role
 of the environment on the phylogeography of bear species, incorporating
 fossil data to characterize the changes in the ecological niche through
 time. We evaluate our approach with the four extant species of bears
 within Ursus, the best represented taxon in the fossil record of the
 family Ursidae. Location: Eurasia and North America. Taxa: Asian black
 bear, Ursus thibetanus; American black bear, U. americanus; Brown bear, U.
 arctos; and Polar bear, U. maritimus. Methods: We built a genetic and a
 geographical database from all published mitochondrial DNA sequences and
 of species occurrence records. We defined the most significant climatic
 variables based on each species ecological realm using correlation
 matrices, and characterized the ecological niches and existing
 environmental conditions with ellipsoid models. We inferred their current
 and Last Glacial Maximum (LGM) ecological niche modellings (ENMs) and
 compared the results with the fossil record. We estimated the times of
 divergence (d‐loop sequences) of lineages and applied a phyloclimatespace
 approach to discern the phylogeographical patterns along each species’
 ecological space. Results: Ecological niche modelling showed wider niches
 for U. thibetanus and U. americanus encompassing higher temperature and
 precipitation, while U. arctos and U. maritimus showed an opposite
 pattern. LGM models were consistent with the fossil record, predicting
 55%–89% of the fossil occurrences (within their suitability areas). The
 phyloclimatespace revealed different degrees of environmental signal in
 the lineages’ phylogeographical patterns and ecological trajectories
 associated with LGM climatic conditions. Results indicated habitat
 tracking and ecological expansion since the LGM towards more extreme
 precipitation and temperature conditions for three species, except U.
 maritimus that showed ecological niche reduction. Main Conclusions:
 Incorporating fossil information from the LGM improved our
 characterization and interpretation of ecological models, by enabling
 definition of the limits of the climatic conditions explored by the
 species in the past. Our approach also provided insights about the
 existing set of environmental conditions shaping the ecological niche
 divergence of Ursus bears. We were able to depict key features of the
 lineages’ evolutionary history, ecology and distribution, revealing the
 dynamics of niche occupation and the environmental signal on the
 phylogeographical patterns of Ursus.
description: CONTENTS: Present Occurrences.csv      
  &lt;--- Present occurrences of the four Ursus species
 Fossil Occurrences LGM.csv    &lt;--- Fossil occurrences of
 the four Ursus species (Last Glacial Maximum)
 Environmental Variables.csv    &lt;--- Environmental values
 of the present occurrences and their respective 'M'
 areas Ursus Haplotypes.nex        &lt;--- Alignment
 of unique haplotypes of the four Ursus species Ursus
 Haplotypes Bios.csv    &lt;--- Estimated environmental values of the
 haplotypes