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A unified framework for diversity gradients: the adaptive trait continuum

Authors

  • Jofre Carnicer,

    Corresponding author
    1. Global Ecology Unit CREAF-CEAB-CSIC, Centre for Ecological Research and Forestry Applications, Edifici C, Campus de Bellaterra (UAB), 08193 Bellaterra, Catalonia, Spain
    2. Community and Conservation Ecology Group, Centre for Life Sciences, Nijenborgh 7, 9747 AG, Groningen, The Netherlands
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  • Constantí Stefanescu,

    1. Global Ecology Unit CREAF-CEAB-CSIC, Centre for Ecological Research and Forestry Applications, Edifici C, Campus de Bellaterra (UAB), 08193 Bellaterra, Catalonia, Spain
    2. Butterfly Monitoring Scheme, Museu Granollers-Ciències Naturals, Francesc Macià 51, 08402 Granollers, Spain
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  • Roger Vila,

    1. Institute of Evolutionary Biology (CSIC-UPF), Passeig Marítim de la Barceloneta 37-49, 08003, Barcelona, Spain
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  • Vlad Dincă,

    1. Institute of Evolutionary Biology (CSIC-UPF), Passeig Marítim de la Barceloneta 37-49, 08003, Barcelona, Spain
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  • Xavier Font,

    1. Department of Plant Biology, University of Barcelona, Diagonal 645, 08028 Barcelona, Spain
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  • Josep Peñuelas

    1. Global Ecology Unit CREAF-CEAB-CSIC, Centre for Ecological Research and Forestry Applications, Edifici C, Campus de Bellaterra (UAB), 08193 Bellaterra, Catalonia, Spain
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Jofre Carnicer, Global Ecology Unit CREAF-CEAB-CSIC, Centre for Ecological Research and Forestry Applications, Edifici C, Campus de Bellaterra (UAB), 08193 Bellaterra, Catalonia, Spain. E-mail: jofrecarnicer@yahoo.es

ABSTRACT

Aim  Adaptive trait continua are axes of covariation observed in multivariate trait data for a given taxonomic group. These continua quantify and summarize life-history variation at the inter-specific level in multi-specific assemblages. Here we examine whether trait continua can provide a useful framework to link life-history variation with demographic and evolutionary processes in species richness gradients. Taking an altitudinal species richness gradient for Mediterranean butterflies as a study case, we examined a suite of traits (larval diet breadth, adult phenology, dispersal capacity and wing length) and species-specific habitat measures (temperature and aridity breadth). We tested whether traits and species-specific habitat measures tend to co-vary, whether they are phylogenetically conserved, and whether they are able to explain species distributions and spatial genetic variation in a large number of butterfly assemblages.

Location  Catalonia, Spain.

Methods  We formulated predictions associated with species richness gradients and adaptive trait continua. We applied principal components analyses (PCAs), structural equation modelling and phylogenetic generalized least squares models.

Results  We found that traits and species-specific habitat measures covaried along a main PCA axis, ranging from multivoltine trophic generalists with high dispersal capacity to univoltine (i.e. one generation per year), trophic specialist species with low dispersal capacity. This trait continuum was closely associated with the observed distributions along the altitudinal gradient and predicted inter-specific differences in patterns of spatial genetic variability (FST and genetic distances), population responses to the impacts of global change and local turnover dynamics.

Main conclusions  The adaptive trait continuum of Mediterranean butterflies provides an integrative and mechanistic framework to: (1) analyse geographical gradients in species richness, (2) explain inter-specific differences in population abundances, spatial distributions and demographic trends, (3) explain inter-specific differences in patterns of genetic variation (FST and genetic distances), and (4) study specialist–generalist life-history transitions frequently involved in butterfly diversification processes.

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