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

Abstract

The influence of Quaternary glaciations on genetic diversity anddemographic and stochastic processes of terrestrial species has been widelystudied worldwide, revealing idiosyncratic patterns and processes for bothhemispheres. Globally, however, research into the relative roles of ice massand climate in the spatial genetic patterns and refugia localization is scarce,and even less on the mechanism by which ice mass shaped intraspecificgenetic diversity. Although its role as a possible barrier is clear, it mayhave also created microclimatic niches or biological corridors, particularlyfor cold- and moisture-adapted flora, as occurs in the Andean Patagonianforests. To investigate the relative effects of climate and ice mass, we carriedout a comparative phylogeographic study of three Patagonian Calceolariaspecies. We analysed species genetic structuring and refugia localization,associated with ice mass fluctuations and climate changes during threemilestones of the last glacial cycle. Our results show the spatio-temporaldecoupled effect of climate and ice mass on species genetic patterns.While climate shaped general intraspecific genetic patterns during the LastGlacial Maximum, the ice mass acted mainly as a generator of micrositesand corridor structuring refugia localization, revealing the ice mass as apromoter rather than an eroding factor of biodiversity.