Revive the Rhinoceros
Geneticists allowed to save the northern white rhino by cloning
Ekaterina Rusakova, N+1
Biologists have assessed whether it is possible to resurrect the virtually extinct northern white rhinoceros, according to Genome Research (Tunstall et al., Evaluating recovery potential of the northern white rhinoceros from cryopreserved somatic cells). Scientists have analyzed the nuclear DNA of several northern rhinos obtained from frozen animal cells that have been collected and cultured for the last 30 years, and found that it is quite suitable for cloning.
It is believed that the northern white rhinos disappeared in the wild, in any case, no traces of them were found after 2007, a few representatives of this species lived in zoos in the USA and the Czech Republic. In 2014, two of the three males remaining on the planet died, and in March of this year, the last of them, Sudan.
To date, only two females have survived, so there are no hopes for the natural survival of the species.
Nevertheless, the researchers believe that it is possible to at least try to resurrect the northern rhinos. In the San Diego Zoo, where animals lived until recently (the last female died in 2015), the tissues of eight unrelated individuals were collected over 30 years. The researchers obtained 12 fibroblast cell lines from them, which are now stored in the zoo's cryobank and which could be used to clone northern white rhinos.
Scientists from the USA, the Czech Republic and the UK, led by Tate Tunstall from the San Diego Zoo, decided to do genome-wide sequencing of fibroblasts to determine the structure of the population and assess its genetic diversity. Geneticists sequenced DNA from nine cell lines, and for comparison conducted genome-wide DNA sequencing of four southern white rhinos.
It turned out that the heterozygosity of northern white rhinos (one of the markers of the genetic diversity of the population) was even slightly higher than that of southern rhinos. Both species had higher genetic diversity than other endangered species, such as marsupial devils and Borneo orangutans. Scientists have also traced the history of both subspecies of rhinos. The number of white rhinos greatly decreased about 800 thousand years ago and began to recover about 100 thousand years ago. Rhinos were divided into subspecies relatively recently, about 80 thousand years ago. The maximum effective size of the population of northern rhinos reached about 40 thousand years ago (about 15 thousand individuals capable of reproduction), the population of southern rhinos – about 50 thousand years ago (about 10 thousand individuals). To date, the effective population size of northern rhinos is estimated at 1300 individuals, the population of southern rhinos is estimated at 2800 individuals.
Earlier, one of the exterminated species of Galapagos turtles received hope for resurrection. Scientists have discovered hybrid turtles of the now extinct and living species on one of the uninhabited islands of the Galapagos Archipelago. Perhaps the turtles of an extinct species were transported to the island by whalers or pirates who used the islands to replenish water and food supplies.
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