Ancient and modern genomes unravel the evolutionary history of the rhinoceros family

Only five species of the once-diverse Rhinocerotidae remain, making the reconstruction of their evolutionary history a challenge to biologists since Darwin. We sequenced genomes from five rhinoceros species (three extinct and two living), which we compared to existing data from the remaining three living species and a range of outgroups. We identify an early divergence between extant African and Eurasian lineages, resolving a key debate regarding the phylogeny of extant rhinoceroses. This early Miocene (∼16 million years ago [mya]) split post-dates the land bridge formation between the Afro-Arabian and Eurasian landmasses. Our analyses also show that while rhinoceros genomes in general exhibit low levels of genome-wide diversity, heterozygosity is lowest and inbreeding is highest in the modern species. These results suggest that while low genetic diversity is a long-term feature of the family, it has been particularly exacerbated recently, likely reflecting recent anthropogenic-driven population declines.We thank the Natural History Museum at the University of Oslo for providing the Javan rhinoceros sample. We thank the Museum of the Institute of Plant and Animal Ecology (UB RAS, Ekaterinburg) for providing the sample of Siberian unicorn. M.T.P.G. was supported by European Research Council (ERC) Consolidator grant 681396 (Extinction Genomics). E.D.L. was supported by Independent Research Fund Denmark grant 8021-00218B . A.C. was supported by an Australian Research Council Laureate Fellowship ( FL140100260 ). T.M.B. is supported by funding from the ERC under the European Union’s Horizon 2020 research and innovation program (grant agreement 864203 ), grant BFU2017-86471-P ( MINECO /FEDER, UE), “Unidad de Excelencia María de Maeztu” funded by the AEI ( CEX2018-000792-M ), Howard Hughes International Early Career , and Secretaria d’Universitats i Recerca and CERCA Programme del Departament d’Economia i Coneixement de la Generalitat de Catalunya ( GRC 2017 SGR 880 ). L.D. was supported by the Swedish Research Council ( 2017-04647 ) and Formas ( 2018-01640 ). We thank Dmitry Bogdanov and Roger Hall for giving us permission to use their rhinoceros artwork