Two ways to be endemic: Alps and Apennines are different functional refugia during climatic cycles

Endemics co-occur because they evolved in situ and persist regionally or
because they evolved ex situ and later dispersed to shared habitats,
generating evolutionary or ecological endemicity centres, respectively. We
investigate whether different endemicity centres can intertwine in the
region ranging from Alps to Sicily, by studying their butterfly fauna. We
gathered an extensive occurrence dataset for butterflies of the study area
(27,123 records, 269 species, in cells of 0.5x0.5 degrees of
latitude-longitude). We applied molecular-based delimitation methods (GMYC
model) to 26,557 COI sequences of Western Palearctic butterflies. We
identified entities based on molecular delimitations and the most recent
checklist of European butterflies and objectively attributed occurrences
to their most probable entity. We obtained a zoogeographic regionalisation
based on the 69 endemics of the area. Using phylogenetic ANOVA we tested
if endemics from different centres differ from each other and from
non-endemics for key ecological traits and divergence time. Endemicity
showed high incidence in the Alps and Southern Italy. The regionalisation
separated the Alps from the Italian Peninsula and Sicily. The endemics of
different centres showed a high turnover and differed in phenology and
distribution traits. Endemics are on average younger than non-endemics and
the Peninsula-Sicily endemics also have lower variance in divergence than
those from the Alps. The observed variation identifies Alpine endemics as
paleoendemics, now occupying an ecological centre, and the
Peninsula-Sicily ones as neoendemics, that diverged in the region since
the Pleistocene. The results challenge the common view of the
Alpine-Apennine area as a single “Italian refugium”.