Close association between flowering time and aridity gradient for Sarcopoterium spinosum in Israel

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.