A long-standing paradigm in ecology has been that contemporary biodiversity requires a diverse array of life to have survived through repeated Pleistocene glaciations when much of the higher latitudes on earth were covered in thick ice sheets. The notion that isolated pockets of ice-free land or “cryptic refugia” also persisted within glaciated areas has been postulated to explain this (1). Under the cryptic refugia scenario, animal and plant life survived, albeit in a scattered distribution and at low densities, in ice-free areas determined largely by topography. These have been proposed to include mountainous areas and deeply incised valleys in terrestrial biomes and marine trenches in ocean biomes. The existence of cryptic refugia is supported by multiple threads of evidence from paleontological, biogeographic, and phylogeographic research (2, 3). They are envisaged to have played a key role in the maintenance of biodiversity through major severe climate events. In PNAS, Fraser et al. (4) present empirical support for the hypothesis that geothermal areas may also have been important as cryptic refuges. The authors apply spatial modeling to a comprehensive terrestrial biodiversity dataset for Antarctica. They identify compelling evidence that geothermal refugia have left indelible and measurable patterns on contemporary biogeography for this continent.
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