Genetics and Distribution of the Italian Endemic Campanula fragilis Cirillo (Campanulaceae)

Campanula fragilis Cirillo is a species distributed in central and southern Italy and includes two subspecies with uncertain taxonomic position and distribution. By means of nuclear and chloroplast markers, we attempted at testing the genetic distinctness of the two subspecies, as well as their possible correspondence with geographical or ecological patterns. After a revision of geographic occurrences based on herbarium data, we carried out species distribution modeling to assess the present and future distribution of this species under different ecological variables, also for conservation purposes. Our findings support the recognition of two weakly differentiated taxa, here accepted at subspecific rank, in agreement with the current taxonomic treatment. We found that C. fragilis subsp. cavolinii is monophyletic and limited to mountains and hills of central Italy. On the contrary, C. fragilis subsp. fragilis shows a higher genetic variability and a broader distribution in central and southern Italy, with a wider altitudinal range from coasts to mountain cliffs. We confirmed that both subspecies are narrowly calcicolous and have similar ecological requirements, but C. fragilis subsp. cavolinii occurs in colder habitats. Our results forecast a significant distribution contraction in the long term.