LAUSR

Abstract The climate gradient in the southeast Mediterranean region offers an opportunity to associate local conditions with adaptive inter-population phenotypic variability. In a common garden experiment, we monitored flowering time and plant biomass in Sarcopoterium spinosum (Rosaceae) representing plant populations along an aridity gradient that in nature differ according to two environmental parameters: elevation and temperature regime. As a significant correlation was found between elevation and the average winter and summer temperatures at the natural sites, elevation was used in the analysis as a proxy for annual temperature regimes. A significant positive correlation was found between flowering day and annual rainfall and elevation, as well as between the aboveground plant biomass and annual rainfall. In addition, a significant negative correlation was found between the flowering day coefficient of variation and the two environmental parameters. Our results show inter-population differentiation in a perennial species, emphasizing the ecological importance of early flowering and trade-offs between growth and reproduction in arid vs. mesic environments.