ABSTRACT Aim Quaternary climatic oscillations have profoundly shaped the genetic structure and geographic distributions of alpine biotas. Understanding how cold‐adapted taxa responded to past climatic shifts is essential for unravelling the processes shaping mountain biodiversity, yet cold‐adapted taxa may have followed divergent refugial histories. We compared two co‐distributed, high‐altitude endemic beetles to test two alternative biogeographic models: (1) persistence in nunatak (i.e., ice‐free mountain peaks) and (2) survival in peripheral glacial refugia. Location Central Apennines, Italy. Taxon The high‐altitude (1700–2700 m a.s.l.) endemic flea‐beetles Longitarsus springeri and Psylliodes biondii . Methods We sampled 112 individuals across 21 mountain sites and integrated mitochondrial and nuclear markers with phylogenetic tree (ML), haplotype‐network, divergence‐time (BEAST), demographic (EBSP) and spatial genetic (SAMOVA) analyses. Results The two species exhibited sharply contrasting patterns of divergence, historical demography and migration. L. springeri showed deep phylogeographic structure with 11 mountain‐specific lineages and demographic stability, consistent with long‐term persistence in isolated nunatak‐like refugia. In contrast, P. biondii displayed shallower genetic structure, highest diversity in the Gran Sasso massif, and a demographic expansion pre‐dating the LGM (~300 kya, MIS 7), consistent with survival in a peripheral refugium followed by range expansion. This pre‐LGM expansion extends the temporal scope of the classical peripheral‐refugia model. Main Conclusions Even ecologically similar, sympatric endemics can follow divergent responses to climatic and environmental shifts. The contrasting histories of L. springeri and P. biondii demonstrate how topographic complexity and glacial dynamics in the central Apennines shaped lineage persistence, range dynamics and genetic structure in alpine biotas and how spatial and temporal dimensions of refugial dynamics can decouple within the same landscape. The central Apennines sky‐island system thus emerges as both a long‐term macro‐refugium and a fine‐scale network of microrefugia driving lineage diversification. A comparative phylogeographic framework offers a powerful approach to understanding how sky‐island systems generate and maintain biodiversity in southern European mountains.
Berrilli et al. (Mon,) studied this question.