Differentiation of ecological niches of Campanula sect. Heterophylla in the Southwestern Alps

Ian Briozzo ¹, Chiara Bonifazio ¹, Davide Casalino ¹, Maria Guerrina ¹, Gabriele Casazza ¹

University of Genoa ¹

This study investigates the ecological niche differentiation among several species of the genus Campanula (section Heterophylla), specifically C. sabatia, C. macrorhiza, C. fritschii, C. cochleariifolia, and C. stenocodon, which share similar habitats in the Southwestern Alps. The study aims to examine spatial, climatic, and microenvironmental overlaps among these species to better understand potential competitive dynamics, with a particular focus on C. sabatia, an endemic and vulnerable species listed in Annex II of the Habitats Directive (92/43/EEC). Occurrence data were obtained from the SILENE, LI.BI.OSS., and WIKIPLANTBASE databases, selecting five sites for each species. In each site, three 4 m² plots were installed, and a 100-point contact grid was used to collect microenvironmental data, including rock, gravel, soil, and vegetation cover. Eight uncorrelated bioclimatic variables were analyzed using Kernel-density plots, while climatic niche overlap was calculated using the model proposed by Broennimann et al. (2012). Geographic overlap was evaluated through the convex hull method in QGIS based on distribution data, and microenvironmental overlap was assessed through Principal Component Analysis (PCA). The climatic analysis revealed two main groups: the first, including C. stenocodon and C. cochleariifolia, is characterized by lower temperatures and higher precipitation, while the second, comprising C. sabatia, C. macrorhiza, and C. fritschii, is associated with higher temperatures and lower precipitation. Geographic and climatic overlap showed significant intersections between C. macrorhiza and C. fritschii, C. stenocodon and C. fritschii, and C. cochleariifolia and C. stenocodon. However, despite these overlaps, the PCA revealed significant microenvironmental differences among these pairs of species, highlighting distinct habitat preferences. In conclusion, C. sabatia shows minimal overlap across spatial, climatic, and microenvironmental levels, suggesting a lower risk of interspecific competition. The risk is especially high for C. stenocodon, as its limited distribution falls entirely within the range of C. cochleariifolia, increasing the chance of interspecific crosses and threatening its genetic stability. This highlights the need for conservation actions to prevent hybridization and preserve the genetic diversity of these species in the Southwestern Alps.

Main author career stage: PhD student

Contribution type: Poster

First choice session: 2. Ecology

Second choice session: 1. Systematics, phylogenetics, biogeography and evolution