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Biotic homogenization as a threat to native affiliate species: fish introductions dilute freshwater mussel's host resources

Authors

  • Karel Douda,

    Corresponding author
    • Department of Zoology and Fisheries, Faculty of Agrobiology Food and Natural Resources, Czech University of Life Sciences Prague, Prague, CZ 165 21, Czech Republic
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  • Manuel Lopes-Lima,

    1. CIMAR-LA/CIIMAR – Centre of Marine and Environmental Research, University of Porto, 4050-123 Porto, Portugal
    2. ICBAS – Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, 4099-003 Porto, Portugal
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  • Mariana Hinzmann,

    1. CIMAR-LA/CIIMAR – Centre of Marine and Environmental Research, University of Porto, 4050-123 Porto, Portugal
    2. ICBAS – Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, 4099-003 Porto, Portugal
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  • Jorge Machado,

    1. CIMAR-LA/CIIMAR – Centre of Marine and Environmental Research, University of Porto, 4050-123 Porto, Portugal
    2. ICBAS – Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, 4099-003 Porto, Portugal
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  • Simone Varandas,

    1. CITAB-UTAD – Centre for Research and Technology of Agro-Environment and Biological Sciences, University of Trás-os-Montes and Alto Douro, Forestry Department, 5001-811 Vila Real, Portugal
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  • Amílcar Teixeira,

    1. CIMO-ESA-IPB – Mountain Research Centre, School of Agriculture, Polytechnic Institute of Bragança, 5301-854 Bragança, Portugal
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  • Ronaldo Sousa

    1. CIMAR-LA/CIIMAR – Centre of Marine and Environmental Research, University of Porto, 4050-123 Porto, Portugal
    2. CBMA – Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, 4710-057 Braga, Portugal
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Correspondence: Karel Douda, Department of Zoology and Fisheries, Faculty of Agrobiology Food and Natural Resources, Czech University of Life Sciences Prague, Kamýcká 129, Prague, CZ 165 21, Czech Republic.

E-mail: k.douda@gmail.com

Abstract

Aim

The indirect consequences of biotic homogenization, the process of a gradual increase in the similarity of regional biotas driven by the combined effects of species invasions and extinctions, are still poorly understood. In this study, we aimed to assess the ability of a native affiliate species to maintain its host resources under the condition of biotic homogenization of host communities.

Location

Central (Vltava River Basin, Czech Republic) and western (Douro River Basin, Portugal) Europe.

Methods

We tested the ability of non-native species to serve as an alternative partner in local host–affiliate relationships. We used a European freshwater mussel, Anodonta anatina, which is considered to be a host generalist of native fish species, and compared the compatibility of its glochidia with native versus non-native fishes in two distinct European regions. Subsequently, we projected the obtained host compatibility data into the recent progress of biotic homogenization and estimated the degree of host dilution.

Results

We found significant differences in the ability of A. anatina glochidia to parasitize the native and non-native fish species in both the central and peripheral parts of the mussel's distribution range. As a result, the increasing presence of non-native species within fish communities across Europe likely significantly decreases the availability of the mussel's host. Biotic homogenization of host communities may interfere with general life history traits (host specificity) of their local affiliate species.

Main conclusions

This study demonstrates that the mixing of regional biotas may lead to an excessive loss of host availability even for host generalists, such as the freshwater mussel A. anatina, with potentially broad consequences for their population dynamics. Conservation strategies of endangered affiliate species need to incorporate the biogeographical context of host–affiliate relationships and particularly the consequences of biotic homogenization.

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