This happens when the alleles are inherited from a common ancestor, such as a shared great-great-great grandparent. Signatures of inbreeding are evident in sequenced genomes at sites where the two copies of a gene match. Move an animal from where it is perfectly happy to an area with a different temperature or humidity, and it might not fare as well.Īnd so the researchers, led by a group from the Centre for Palaeogenetics in Stockholm, with team members from the US, UK, Malaysia, Denmark, Norway, Ireland, Germany, and South Africa, sought clues in genomes to guide the “translocation” of male Sumatran rhinos from their home turf to help populate other groups. But at the same time, interfering with natural mating by moving males may disrupt the adaptations that have come to persist that enable small groups to survive in their particular environments. One way to save the Sumatran rhino may be to transport males, or their sperm, from one natural population to another, in an attempt to promote genetic diversity that might in turn improve health. The mating of close relatives matches up those deleterious recessive alleles (gene variants), upping the odds of genetic disease. The few individuals maintain only part of the long-ago genetic diversity, as effects of mutations that make it through are amplified. Shrinking populations trigger a vicious cycle. The Malayan contingent is already gone, and the Borneo population consists of one female and fewer than 10 males. Today conservationists think that fewer than 100 animals exist. The numbers began to fall again in the 1930s, and then precipitously so, by about 70 percent, during the past two decades due to poaching and habitat destruction. The small and separated Sumatran rhinoceros populations plunged at the end of the Pleistocene, but the animals remained from the Himalayan foothills to Borneo and Sumatra. Ash spewed across the Indian Ocean, Indian Peninsula, and South China Sea. The rhinos diverged further within those groups as they became separated into small geographic areas called refugia, dramatically so after a giant volcano, Mount Toba, erupted about 71,000 years ago and killed many animals. An ancestral species split into three about 360,000 years ago. (Females do not like mating in zoos.)Ĭlues to the evolutionary history of the animals lie in their DNA sequences. The tiny populations have been shrinking, as the animals die faster than they can replace themselves. Stranded animals mated with relatives, leading over the generations to diminishing genetic diversity as recessive alleles (gene variants) doubled up and caused disease. The Sumatran rhino is critically endangered, a result of periodic isolation of populations as sea levels rose and fell during the Pleistocene epoch from 2.6 million to 11,700 years ago. It’s more closely related to the woolly rhinos of the ice age than the other four species (Indian, Javan, and white and black in Africa). “Genomic insights into the conservation status of the world’s last remaining Sumatran rhinoceros populations” appears in Nature Communications.Ī Sumatran rhino is the smallest rhino, weighing just under a ton and standing nearly five feet. Taking a census is challenging, although they “sing.” It isn’t known how many of them exist, exactly, but the number is small.Ī multinational research team has unearthed clues in the genomes of 21 of the animals, five “historical” from the Malay Peninsula where they are extinct, and 16 modern genomes from the remaining populations on Sumatra and Borneo. Sumatran rhinoceroses are solitary creatures that browse the dense rainforests of Borneo and Sumatra, living in small, scattered, shrinking groups.
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