Ecological and historical factors affecting distribution pattern and richness of endemic plant species: the case of the Maritime and Ligurian Alps hotspot

Diversity and Distributions, (Diversity Distrib.) (2008) 14, 47–58 Ecological and historical factors affecting distribution pattern and richness of endemic plant species: the case of the Maritime and Ligurian Alps hotspot Gabriele Casazza1, Elena Zappa2, Mauro G. Mariotti1, Frédéric Médail3 and Luigi Minuto1* 1DIP.TE.RIS. – Università di Genova, Corso Dogali 1M, 16136 Genova, Italy, 2Centro di Servizi di Ateneo Giardini Botanici Hanbury – Università di Genova, Corso Montecarlo 43, La Mortola, I-18039 Ventimiglia, Italy, 3Institut Méditerranéen d’Ecologie et de Paléoécologie (IMEP, CNRS UMR 6116) – Université Paul Cézanne (Aix-Marseille III), Europole Méditerranéen de l’Arbois, Bâtiment Villemin, BP 80, F –13545 Aix-en-Provence cedex 04, France The aim of this study was to test a method to locate all the foci, centres, and areas of endemism in a biodiversity hotspot in order to understand the influence of ecological and historical factors on the distribution pattern and to identify priority areas for future conservation projects. The study area was the Maritime and Ligurian Alps hotspot. Analyses were performed on the presence/absence matrix of 36 vascular plant taxa endemic to the study area. For each operational geographical unit, the number of endemic taxa present was counted. Additionally, the weighted endemism value was calculated. Areas of endemism were distinguished using cluster analysis and parsimony analysis of endemicity. The influence of ecological characteristics and historical factors was evaluated using Multi-Response Permutation Procedure and the Nonparametric Multiplicative Regression. The Indicator Species Analysis (INDVAL) method was used to identify the species characterizing the areas of endemism. Our results show the importance and location of four main areas of endemism within the Maritime and Ligurian Alps and explain the distribution pattern of endemic plants. These areas are easily interpreted by historical and ecological factors, and INDVAL indicates which taxa took part in the history of each endemism area. Keywords Cluster analysis, geological substrate, glacial refugia, historical factors, Ligurian Alps, Maritime Alps, parsimony analysis of endemism, species richness, vascular plants