Glacial Legacies - How refugial dynamics shaped the evolution of the Alpine endemic bush-cricket Anonconotus italoaustriacus

Abstract

Mountain ranges like the European Alps harbor large endemic biodiversity shaped by Pleistocene climatic oscillations. The flightless bush-cricket Anonconotus italoaustriacus, endemic to the Southern Limestone Alps (SLA) and the eastern Central Alps (CA), provides an ideal model to study the evolutionary and refugial dynamics of endemic alpine arthropods. Using genomic SNP data, we employed phylogenetic analyses, Bayesian clustering, and demographic modeling to investigate the species evolutionary history and its refugial dynamics. Our results support a scenario of survival in multiple peripheral refugia during the Last Glacial Period (LGP; 115-11.7 ka), with populations in the southern SLA and eastern CA exhibiting the highest private allelic richness. Postglacial recolonization of interior alpine regions occurred exclusively from refugia on the southeastern margin of the SLA, most likely facilitated by open habitat corridors along transversal valleys. In contrast, populations in the southern SLA exhibited long-term isolation and distributional stasis, emphasizing the importance of small, stable refugia in preserving genetic diversity. We propose that polyandry, a reproductive strategy of A. italoaustriacus, contributed to its resilience by maintaining high genetic diversity despite repeated bottlenecks and habitat fragmentation. These findings highlight the importance of integrating evolutionary history into conservation strategies, particularly for alpine endemics with fragmented distributions. Protecting both long-term stable refugia and dynamic evolutionary hotspots is critical for the conservation of A. italoaustriacus and other high-altitude arthropods in the face of ongoing environmental change.