Melting memories: decoupled effects of ice and climate during the Quaternary shaped genetic diversity in Andean Calceolaria species

The influence of Quaternary glaciations on genetic diversity and demographic and stochastic processes of terrestrial species has been widely studied worldwide, revealing idiosyncratic patterns and processes for both hemispheres. Globally, however, research into the relative roles of ice mass and climate in the spatial genetic patterns and refugia localization is scarce, and even less on the mechanism by which ice mass shaped intraspecific genetic diversity. Although its role as a possible barrier is clear, it may have also created microclimatic niches or biological corridors, particularly for cold- and moisture-adapted flora, as occurs in the Andean Patagonian forests. To investigate the relative effects of climate and ice mass, we carried out a comparative phylogeographic study of three Patagonian Calceolaria species. We analysed species genetic structuring and refugia localization, associated with ice mass fluctuations and climate changes during three milestones of the last glacial cycle. Our results show the spatio-temporal decoupled effect of climate and ice mass on species genetic patterns. While climate shaped general intraspecific genetic patterns during the Last Glacial Maximum, the ice mass acted mainly as a generator of microsites and corridor structuring refugia localization, revealing the ice mass as a promoter rather than an eroding factor of biodiversity.