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Phylogenetic beta diversity of native and alien species in European urban floras

Authors

  • Carlo Ricotta,

    Corresponding author
    1. Department of Environmental Biology, University of Rome ‘La Sapienza’, Piazzale Aldo Moro 5, 00185 Rome, Italy
      Carlo Ricotta, Department of Environmental Biology, University of Rome ‘La Sapienza’, Piazzale Aldo Moro 5, 00185 Rome, Italy. E-mail: carlo.ricotta@uniroma1.it
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  • Frank A. La Sorte,

    1. Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06520, USA
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  • Petr Pyšek,

    1. Department of Invasion Ecology, Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Průhonice, Czech Republic
    2. Department of Ecology, Faculty of Science, Charles University, Viničná 7, CZ-128 01 Praha 2, Czech Republic
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  • Gillian L. Rapson,

    1. Ecology Group, Institute of Natural Resources, Massey University, Palmerston North, New Zealand
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  • Laura Celesti-Grapow,

    1. Department of Environmental Biology, University of Rome ‘La Sapienza’, Piazzale Aldo Moro 5, 00185 Rome, Italy
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  • Ken Thompson

    1. Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
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Carlo Ricotta, Department of Environmental Biology, University of Rome ‘La Sapienza’, Piazzale Aldo Moro 5, 00185 Rome, Italy. E-mail: carlo.ricotta@uniroma1.it

ABSTRACT

Aim  Human activities have weakened biogeographical barriers to dispersal, increasing the rate of introduction of alien plants. However, their impact on beta diversity and floristic homogenization is poorly understood. Our goal is to compare the phylogenetic beta diversity of native species with that of two groups of alien species, archaeophytes and neophytes (introduced before and after ad 1500, respectively), across European urban floras to explore how biological invasions affect phylogenetic turnover at a continental scale.

Location  Twenty European cities located in six countries between 49 and 53° N latitude in continental Europe and the British Isles.

Methods  To compare the phylogenetic beta diversity of native and alien species we use the average phylogenetic dissimilarity of individual floras from their group centroid in multivariate space. Differences in phylogenetic beta diversity among different species groups are then assessed using a randomization test for homogeneity of multivariate dispersions.

Results  Across European urban floras, and when contrasted with natives, archaeophytes are usually associated with lower levels of phylogenetic beta diversity while neophytes tend to increase phylogenetic differentiation.

Main conclusions  While archaeophytes tend to promote limited homogenization in phylogenetic beta diversity, because of their diverse geographical origin together with short residence times in the invaded regions, neophytes are not promoting biotic homogenization of urban floras across Europe. Therefore, in spite of the increasing rate of alien invasion, an intense phylogenetic homogenization of urban cities is not to be expected soon.

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