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Arthropod assemblage homogenization in oceanic islands: the role of indigenous and exotic species under landscape disturbance

Authors

  • Margarita Florencio,

    Corresponding author
    1. Departamento de Ciências Agrárias, Azorean Biodiversity Group (CITA-A) and Platform for Enhancing Ecological Research and Sustainability (PEERS), Universidade dos Açores, Angra do Heroísmo, Terceira, Azores, Portugal
    • Correspondence: Margarita Florencio, Azorean Biodiversity Group (CITA-A) and Platform for Enhancing Ecological Research and Sustainability (PEERS), Departamento de Ciências Agrárias, Universidade dos Açores, 9700-042 Angra do Heroísmo, Terceira, Azores, Portugal.

      E-mail: margarita.florencio@uac.pt

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  • Pedro Cardoso,

    1. Departamento de Ciências Agrárias, Azorean Biodiversity Group (CITA-A) and Platform for Enhancing Ecological Research and Sustainability (PEERS), Universidade dos Açores, Angra do Heroísmo, Terceira, Azores, Portugal
    2. Finnish Museum of Natural History, University of Helsinki, Helsinki, Finland
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  • Jorge M. Lobo,

    1. Departamento de Ciências Agrárias, Azorean Biodiversity Group (CITA-A) and Platform for Enhancing Ecological Research and Sustainability (PEERS), Universidade dos Açores, Angra do Heroísmo, Terceira, Azores, Portugal
    2. Departamento de Biogeografía y Cambio Global, Museo Nacional de Ciencias Naturales (CSIC), C/José Gutiérrez Abascal, 2, 28006, Madrid, Spain
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  • Eduardo Brito de Azevedo,

    1. Centro de Estudos do Clima, Meteorologia e Mudanças Globais (CMMG), Dep. de Ciências Agrárias, Universidade dos Açores, Angra do Heroísmo, Portugal
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  • Paulo A.V. Borges

    1. Departamento de Ciências Agrárias, Azorean Biodiversity Group (CITA-A) and Platform for Enhancing Ecological Research and Sustainability (PEERS), Universidade dos Açores, Angra do Heroísmo, Terceira, Azores, Portugal
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Abstract

Aims

Human landscape disturbance can drive the degradation of natural environments, thereby contributing to indigenous (endemic and native non-endemic) species extinctions, facilitating the establishment of exotic species and ultimately resulting in more similar species compositions over time and space. We assessed whether similarities in epigean arthropod assemblages differ between indigenous and exotic species in an oceanic archipelago, and we also examined whether such assemblage similarities depend on the most dominant species, the island, the type of habitat, the degree of landscape disturbance or local environmental variables.

Location

Four oceanic islands in the Azores archipelago, Portugal.

Methods

We examined the degree of assemblage similarity and the effect of environmental variables and spatial disturbance to explain the epigean arthropod distributions for indigenous and exotic species.

Results

Exotic species increased overall assemblage similarity. Distinct arthropod assemblages occurred on the different islands and in the different habitats. Assemblage differences between the habitats depended on the island. This pattern was largely explained by the abundance patterns of the most abundant indigenous and exotic species (ten indigenous and ten exotic species accounted for 75% of total individuals). In comparison with the high explanatory capacity of the habitats and islands per se, local environmental variables and disturbance hardly explained the assemblage composition in both groups of species.

Main conclusions

We demonstrate that exotic species promote assemblage homogenization on these oceanic islands, and that such process is contingent and independent between islands and habitats. General habitat characteristics seemed to be the main driver of assemblage structure, independently of the different climatic conditions or disturbance levels.

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