Thought to be nearly extinct at the beginning of the 20th century after being reduced to a single population of 20–50 individuals ( Emslie 2012), subsequent conservation efforts have led to a dramatic recovery of this subspecies. simum simum) is currently the most abundant rhinoceros in the world, with about 20,000 individuals living primarily in South Africa ( Emslie 2012). Despite continuing threats, including poaching and habitat destruction, the southern population of white rhinoceros known as the southern white rhinoceros (SWR C. Rhinoceroses as a group are particularly affected, with three of the five extant species listed as critically endangered (Javan, Sumatran, and black rhinoceroses), one listed as vulnerable (greater one-horned rhinoceros), and only one, the white rhinoceros ( Ceratotherium simum), listed as near threatened. The worldwide loss of wildlife has been described as the sixth mass extinction ( Wake and Vredenburg 2008 Kolbert 2014), with 22% of mammals at risk of extinction ( ). This work demonstrates the value of the northern white rhinoceros cryopreserved genetic material as a potential gene pool for saving this subspecies from extinction. Inbreeding, as measured by runs of homozygosity, appears slightly higher in the southern than the northern white rhinoceros. The two white rhinoceros subspecies appear to be closely related, with low genetic admixture and a divergent time <80,000 yr ago. We present the first sequenced genomes of the northern white rhinoceros, which show relatively high levels of heterozygosity and an average genetic divergence of 0.1% compared with the southern subspecies. In this work, we analyzed genome-wide levels of genetic diversity, inbreeding, population history, and demography of the white rhinoceros sequenced from cryopreserved somatic cells, with the goal of informing how genetically valuable individuals could be used in future efforts toward the genetic rescue of the northern white rhinoceros. Its extinction would appear inevitable, but the development of advanced cell and reproductive technologies such as cloning by nuclear transfer and the artificial production of gametes via stem cells differentiation offer a second chance for its survival. The critically endangered northern white rhinoceros is believed to be extinct in the wild, with the recent death of the last male leaving only two remaining individuals in captivity.

White rhinoceros population increasing