Climate and genetic diversity change in mammals during the Late Quaternary

Conservation decisions and future scenarios are in need of past baselines on climate change impacts in biodiversity. Although we know that climate change has contributed to diversity shifts in some mammals1,2,3,4,5,6,7, previous research often assumed that climate change is invariable across species ranges. We are therefore still ignorant of the true rates of climate change experienced by species assemblages over the last millennia, their impacts on intraspecific diversity, and how they compare to future climate change projections. Here, we use more than 9,000 Late Quaternary records, including fossils and ancient and modern DNA sequences, millennial-scale paleoclimatic reconstructions over the last 50,000 years and future climate change projections to document rates of climate change velocity and dynamics in genetic diversity experienced by an assemblage of 16 extinct and extant Holarctic mammal species. Extinct megafauna experienced velocities more than 15 times faster than the extant species, up to 15.2 km per decade. Notably, extant large-bodied grazers lost almost a 65% of their pool of genetic diversity since the Late Pleistocene, which indicates reduced ability to adapt to on-going global change. Additionally, mammal species experienced overall climate change velocities slower than that projected for the end of the 21st century but punctuated by comparable fast climate change episodes. Our results provide baselines on the impacts of ongoing and future climate change on the diversity of mammal species.