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Does local habitat fragmentation affect large-scale distributions? The case of a specialist grassland bird

Authors

  • Luís Reino,

    Corresponding author
    1. CEF- Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade Técnica de Lisboa, Lisboa, Portugal
    2. EDP Biodiversity Chair, CIBIO-Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Vairão, Portugal
    • Rui Nabeiro Biodiversity Chair, CIBIO-Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade de Évora, Évora, Portugal
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  • Pedro Beja,

    1. EDP Biodiversity Chair, CIBIO-Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Vairão, Portugal
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  • Miguel B. Araújo,

    1. Rui Nabeiro Biodiversity Chair, CIBIO-Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade de Évora, Évora, Portugal
    2. Museo de Nacional de Ciencias Naturales, CSIC, Madrid, Spain
    3. Center for Macroecology, Evolution and Climate, University of Copenhagen, Universitetsparken, Copenhagen, Denmark
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  • Stéphane Dray,

    1. Université de Lyon, F-69000, Lyon, Université Lyon 1, CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, Villeurbanne, France
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  • Pedro Segurado

    1. CEF- Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade Técnica de Lisboa, Lisboa, Portugal
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Correspondence: Luís Reino, CIBIO-Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, Rua Padre Armando Quintas, 4485-661, Vairão, Portugal.

E-mail: luis.reino@cibio.up.pt

Abstract

Aim

Although the negative effects of habitat fragmentation have been widely documented at the landscape scale, much less is known about its impacts on species distributions at the biogeographical scale. We hypothesize that fragmentation influences the large-scale distribution of area- and edge-sensitive species by limiting their occurrence in regions with fragmented habitats, despite otherwise favourable environmental conditions. We test this hypothesis by assessing the interplay of climate and landscape factors influencing the distribution of the calandra lark, a grassland specialist that is highly sensitive to habitat fragmentation.

Location

Iberia Peninsula, Europe.

Methods

Ecological niche modelling was used to investigate the relative influence of climate/topography, landscape fragmentation and spatial structure on calandra lark distribution. Modelling assumed explicitly a hierarchically structured effect among explanatory variables, with climate/topography operating at broader spatial scales than landscape variables. An eigenvector-based spatial filtering approach was used to cancel bias introduced by spatial autocorrelation. The information theoretic approach was used in model selection, and variation partitioning was used to isolate the unique and shared effects of sets of explanatory variables.

Results

Climate and topography were the most influential variables shaping the distribution of calandra lark, but incorporating landscape metrics contributed significantly to model improvement. The probability of calandra lark occurrence increased with total habitat area and declined with the number of patches and edge density. Variation partitioning showed a strong overlap between variation explained by climate/topography and landscape variables. After accounting for spatial structure in species distribution, the explanatory power of environmental variables remained largely unchanged.

Main conclusions

We have shown here that landscape fragmentation can influence species distributions at the biogeographical scale. Incorporating fragmentation metrics into large-scale ecological niche models may contribute for a better understanding of mechanism driving species distributions and for improving predictive modelling of range shifts associated with land use and climate changes.

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