Late Quaternary Climate‐Driven Shifts in Arctic Plant Distributions

Aim Glaciation events shaped the present distribution of many plants and their biodiversity in the northern hemisphere. Glacial expansion forced many species south and came with much colder global temperatures, while glacial recession brought warmer temperatures and newly colonisable land without competition. However, the changes in plant diversity associated with glacial retreat and the ensuing climatic changes are not well understood. In this study, we quantify Late Quaternary climate‐driven changes in Arctic plant diversity by integrating climatic shifts in species distributions since the last glacial maximum (20–16 kya) and mid‐Holocene (5 kya) across the circumpolar arctic. Location The geographic arctic, 66° N. Taxon Vascular plants. Methods We built species distribution models using phyloregion v.1.0.9 in R using occurrence data from the Global Biodiversity Information Facility and bioclimatic variables from Worldclim v2.1 for the present‐day and v.1.4 for both the mid‐Holocene and Last Glacial Maximum. Results and Discussion We found limited evidence for decreases in weighted endemism and species richness, along with north and south species range changes contrary to expectations of increased alpha diversity since the last glacial maximum. Decreases in species alpha diversity, while already quite low in the arctic, may be reflective of an increasingly variable arctic climate that disfavors plants with a slow dispersal ability. This is especially important given the projected increase in global temperature across many shared socioeconomic pathway scenarios and can be contrasted with our results of the Mid‐Holocene, which was about one degree warmer than it is today. The arctic is presently warming at about two to five times the rate of the mid‐latitudes and equator and understanding how plants have responded in the past will help inform on how they may change in the future.