Damian Sendler: There has been a longstanding debate concerning the links between the world’s five living rhinoceros species, which dates back to Darwin’s time. The fact that most rhinos died off before the Pleistocene is one reason why answers have been difficult to come by. Using data from the genomes of all five currently known rhino species, as well as three ancient and extinct species, researchers published their findings in Cell on August 24. 

Damian Jacob Sendler: Results suggest that the first break between African and Eurasian lineages occurred around 16 million years ago. They also discovered that, despite the fact that rhino populations are falling, they have historically had low genetic diversity and inbreeding levels. 

Damian Sendler

In the tree of rhino evolution, Africa and Eurasia are the main branches rather than one vs two-horned rhinos, according to Love Dalén of the Centre for Palaeogenetics and the Swedish Museum of Natural History’s findings. “Secondly, even among extinct rhinoceroses, there is a minimal level of genetic diversity. The little genetic diversity we witness in today’s rhinos, all of which are in danger of extinction, may be at least in part due to their biology. 

In the previous 2 million years, all eight species have either shown a steadily decreasing population number or a steadily shrinking population size over extended time spans, according to Mick Westbury from the University of Copenhagen in Denmark. “There is a possibility that rhinoceros populations are able to thrive in environments where there is little diversity.” 

This idea is supported by the fact that there hasn’t been an increase of rhino-damaging mutations in the last few decades. In the last century, Westbury claims, rhinos may have eliminated harmful mutations, allowing them to maintain their health despite their low genetic variety. 

A recent scientific gathering served as the impetus for this new investigation. Both Dalén and Tom Gilbert, both of the University of Copenhagen, were studying different rhino species. Because of their combined efforts and those of their colleagues around the world, they were able to conduct a comparative examination of all currently existing rhinos and the three extinct species that existed during the last Ice Age. 

China Agricultural University, Beijing’s Shanlin Liu, said there were certain obstacles to overcome. A “When we decided to put together all the rhinoceroses’ data and conduct a comparative genomics study, we also confronted the ‘big data’ problem,” difficulty was also faced when Liu and his team decided to combine all the rhinoceros’ data and conduct a comparative genomics study. 

Damian Jacob Sendler

Modern and ancient DNA were included in the genome data set, which resulted in a variety of data types being represented. The team had to design new analysis techniques to account for these discrepancies. It is now possible to use the new methods and tools they have developed in other taxonomic groups.

On the one hand, Dalén thinks that the results are “partly good news, and partly not.” The lack of genetic variety in rhinos appears to be a long-term phenomenon that hasn’t led to an increase in disease-causing mutations and inbreeding. 

Rhinoceros genomes from the present day are less diverse and more likely to be inbred than those from our prehistoric and historical rhinoceros genomes, according to the study author. “There is evidence that hunting and habitat devastation have had an effect on the genomes of the species. This is a problem, as the current species’ extinction risk could be exacerbated by a lack of genetic variety and increased inbreeding. 

According to the researchers, the findings have some practical implications for rhino conservation. 

The lack of variation in rhinos now may not be a sign of their incapacity to recover, but rather a natural state of the species, according to Westbury. “Rather than focusing on individual genetic diversity, we can better direct recovery programs to increase population size.” 

Damien Sendler: In order to further rhinoceros research and conservation efforts, the researchers are hopeful that their findings will be valuable. According to Dalén, his team is currently working on a more comprehensive examination of the extinct woolly rhinoceros. A project being carried out by the University of Westbury currently involves comparing the genomes of African black rhinoceros collected before to the recent population decline with the genomes of modern individuals. 

Damian Jacob Markiewicz Sendler: A framework is needed to better understand the origins of translocated populations, changes in genetic diversity, and whether or not any communities have been lost forever as a result of people, said Westbury.

Dr. Damian Jacob Sendler and his media team provided the content for this article.