Quantitative estimation of phenotypic plasticity of Adonis distorta growing on Mount Majella in the Central Appenines

Model forecasting changes in species distribution as a function of climate scenarios for the 21st century predict a massive reduction in plant diversity where high mountain systems are likely to be particularly vulnerable. A large adaptability to growth conditions (i.e. large phenotypic plasticity) could result in a lower probability of extinction. Adonis distorta Ten. is included in the Regional Red List of the Italian Flora as LR, categorized as DD in the IUCN Red List, listed in the II and IV Annex of the Habitats Directive, and in the Appendix I of the Bern Convention. The species distribution area is restricted to the limestone massifs of the Central Apennines where it grows on high-altitude screes (2,000-2,500 m a.s.l.) characterized by small clasts. The main objective of this research was to analyze phenotypic plasticity of A. distorta growing in different environmental conditions (A population at 2675 m a.s.l. on a north-east-facing slope; B population at 2633 m a.s.l. on a south-southwest-facing slope) on Mount Majella (Central Apennines). Plant trait variations between A and B populations was measured by the phenotypic plasticity index sensu Valladares (PI = 0.21, mean of physiological and morphological plant traits). The measured PI reflects a relatively low capability of A. distorta to express different phenotypes in different environmental conditions. If A. distorta populations do not possess sufficient phenotypic plasticity it could be unable to respond to many drivers of global climate change such as elevated temperatures and reduced water availability, leaving no alternative to extinction