Invasion Amid the Shadows: Ecophysiological Dissimilarity and Microhabitat Constraints on an Exotic Succulent in a Mediterranean Ecosystem.

Prevention is the most cost-effective strategy for managing plant invasions, which includes defining the potential of exotic species to inhabit different environmental conditions. The limiting similarity hypothesis suggests that resemblance to native species facilitates the establishment and spread of exotics in a non-native range. However, this similarity has rarely been quantified in terms of the physiological strategies used to cope with seasonal environmental variability. Here, we explored for the first time the multivariate ecophysiological similarity between an exotic species and the native community to assess where the invader might succeed. Specifically, we contrasted the physiological annual response of the declared potential invader Aptenia cordifolia relative to six coexistent native species in two contrasting environmental conditions (under canopy and at high irradiance) in a Mediterranean-type ecosystem. The invasive species exhibited distinct physiological responses, demonstrating partial alignment with native traits under specific conditions. At the high irradiance site, the exotic species was the least efficient at counteracting both summer and winter stresses; whereas in the under-canopy habitat, it exhibited greater ecophysiological dissimilarity from the native community. Our results score the potential of multivariate physiological analysis for guiding habitat prioritization in invasion management and biodiversity conservation in Mediterranean-type ecosystems.