Linking within- and among-population variation in early plant performance reveals the potential for persistence in novel edaphic environments in fragmented populations of the Mediterranean cliff carnation Dianthus rupicola

Background and aims: Local adaptation to edaphic conditions might produce edaphic specialization, possibly limiting the potential for persistence in novel environments. Therefore, evaluating how different populations can cope with novel edaphic environments is crucial to forecast species survival. Methods: We conducted a reciprocal transplant experiment in greenhouse conditions in five Dianthus rupicola populations. We characterized the edaphic environments and estimated, in twelve maternal seed families per population, germination performance, seedling survival and photosynthetic efficiency in home vs. foreign soils. These data were used to test for local adaptation to the edaphic environment and to estimate genotype-by-environment interactions (G × E). Lastly, to estimate the additive genetic variance of each population, we quantified levels of genomic inbreeding. Results: In four populations, we found strong patterns of local adaptation in germination performance and seedling survival, but not in photosynthetic efficiency. Populations showed similar extents of genetic diversity. Also, four populations were characterized by a significant G × E in plant performance verified by an increase in the expression of variance. However, the frequency of families being able to germinate in such environments was different among the populations. Conclusion: Our study shows that the edaphic environment can lead to strong natural selection in early plant life-cycle stages. However, maternal families that overcome the first critical phases show a wide tolerance to transplant soils. These families hidden within a population might have the potential to adapt to novel edaphic environments enhancing species survival in fragmented Mediterranean habitats.