Good news for Sumatran rhinos

This is great news that the international team released on April 26, 2021 in a review Natural communications. Recent populations of Sumatran rhinoceros (Dicerorhinus sumatrensis) suffer only from low levels of inbreeding.

Critically endangered species

TheInternational Union for Conservation of Nature there are only 30 mature Sumatran rhinos in the world. The species is also critically endangered and is one of the most endangered mammal species in the world. “It is estimated that population size (…) has decreased by about 70% over the last 20 years due to poaching and habitat change“says the study. Recent reports have also highlighted health problems in these animals and fertility. Scientists feared that these phenomena were the result of high inbreeding in populations still present. In this new study, researchers sequenced the genome 21 of the modern rhino or.” historical “specimens from museums older than 100 years. 16 specimens represented the modern populations of Borneo, Sumatra and the Malay Peninsula (recently extinct population). In this way, the authors were able to assess blood relationship affecting populations, but also the frequency of a particular mutation could prove harmful to the survival of the species.

No inbreeding … right now

The researchers were pleasantly surprised by some of the results obtained.

To our surprise, we found relatively low levels of inbreeding and great genetic diversity in the current populations of Borneo and Sumatra.“, remark in Statement Johanna von Seth, one of the lead authors of the study. This phenomenon could be explained by the relatively recent decline of these populations. Inbreeding has not yet had time to rule for generations. According to the authors of this study, this is good news: there is still time to save the species, preserving its genetic diversity. And we must act quickly and not announce victory too quickly: “the population of the Malay Peninsula experienced an increase in inbreeding just before death“The study reveals. In addition, genomic analyzes have yielded disturbing news: potentially harmful mutations have been found in the DNA of some animals.”If populations do not start to increase, there is a high risk that inbreeding levels will start to rise and as a result genetic diseases will become more common.“, warns Nicolas Dussex, co-author of this study.

Two subpopulations treated as one set?

Increasing the size of these populations would be an ideal solution to rescue the populations of Borneo and Sumatra without any problems, but the challenge is considerable. Rhino transfer between populations and the use of artificial insemination can also be a solution to save an entire species consisting of two subspecies: Sumatra (DsSumatrensis) and Borneo (DS Harrissoni). “Given the high risk of rhinoceros extinction in Sumatran, it could be argued that the remaining populations should be managed as a metapopulation (set, editor’s note), because the increase in evolutionary potential and the chance of survival of a species by genetic rescue may exceed the value of maintaining evolutionary lines“, explain the scientists.”With less than 100 individuals left, there have recently been proposals to manage species as a single unit and to increase gene flow by translocating or exchanging gametes from different populations.“, also underscores the study. But precautions will still need to be taken if the species are really to be managed as a single group: the transferred individuals must not have mutations that could endanger the host population.

With little evidence of a recent cross between kinship in the two surviving populations and few fixed harmful alleles, it appears that the long-term survival of the Sumatran rhino is not immediately compromised by harmful genetic factors characteristic of small populations, rejoice the authors of this new study. However, given the extremely small size of the surviving populations in Borneo and Sumatra, it seems inevitable that crossbreeding will increase in the near future.“if the situation does not improve.

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