How glaciation impacted evolutionary history and contemporary genetic diversity of flora and fauna in the British Isles

ABSTRACT Ice coverage not only affects the climate and landscape of geographical regions but has impacted species composition, the fragmentation and isolation of populations, and the colonisation routes of species post-glaciation. Major advancements in generating genetic data and applying sophisticated analyses to accurately model the demographic and colonisation history of animal and plant species has allowed evolutionary biologists novel insights. Meanwhile, physical geographers have made major advancements in reconstructing glacial history. However, the information flow between the geographic and evolutionary fields on this topic remains limited; consequently, evolutionary studies on contemporary biodiversity and species colonisation tend to be vague about the role of glacial history, while evolutionary and biodiversity information is rarely leveraged when discussing historical glaciation. In this review, we bring together current knowledge on the changing patterns of ice coverage in the British Isles from the maximum extent of the British-Irish ice sheet (BIIS) ca. 27 ka through to the end of large-scale ice coverage at the start of the Holocene period ca. 11.5 ka. We do so to then highlight how glaciation affected species composition during this time period and the subsequent colonisation of temperate flora and fauna and the patterns of genetic variation seen in them.