Grooming mountain gorillas in Bwindi National Park, in a multi-silverback group which is specific to mountain gorillas. Credit: Mike Cranfield, Gorilla Doctors
Scientists discover gene flow from an extinct gorilla population to eastern gorillas.
An international research study, recently published in the journal Nature Ecology and Evolution, provides a better insight into the evolutionary history of gorillas. The researchers, led by the University of Vienna (Austria) and the Institute of Evolutionary Biology (IBE) in Barcelona (Spain), evaluated the genomes of gorillas using modern statistical approaches, including neural networks.
The team discovered a gene circulation occasion in this types of apes, which is carefully associated to human beings, from a currently extinct lineage to gorillas living today. This is comparable to how modern-day human beings and bonobos have maintained genes from extinct groups, which can still be found in our genomes.
Humans and gorillas share an interesting element in typical: In both species, their DNA was mixed throughout evolution by mating with people from other groups which are already extinct today– and for this factor, there was an introgression of genes from one group to another. In the course of evolutionary history, modern-day humans have exchanged genes with Denisovans and neanderthals.
Mountain gorilla mother and baby together with another adult woman throughout a rest period. Credit: Mike Cranfield, Gorilla Doctors
Their tradition can still be discovered in the genome of many humans nowadays. There are couple of comparable studies resolving this concern in fantastic apes, specifically gorillas, due to the fact that there are just a few fossils of our close living relatives, unlike the Homo sapiens, from which ancient DNA could be drawn out for analysis. The genomes of people living today are the only method to rebuild their evolutionary history, which is of particular importance, because gorillas are threatened with termination in the wild.
Gene circulation from ghost population provides new insights into evolutionary history
Gorillas are made up of 2 species (eastern and western gorillas), each of which has two subspecies: Western gorillas include the western lowland gorillas and the cross-river gorillas, while eastern gorillas include the eastern lowland gorillas and the carefully related mountain gorillas. In the existing research study, the leading teams of Tomas Marques-Bonet at the IBE and Martin Kuhlwilm at the University of Vienna, with partnership of Chris Tyler-Smith and Yali Xue, from the Sanger Institute, examined entire genomes of individuals from all 4 subspecies, including freshly sequenced mountain gorilla genomes from Bwindi National Park in Uganda, one of just two locations where the couple of remaining mountain gorillas can be discovered.
Mountain gorilla mom and baby throughout a pause. Credit: Mike Cranfield, Gorilla Doctors
Innovative statistical approaches including the integration of neural networks exposed a surprising outcome: 40,000 years back, genes were exchanged in between a now-extinct gorilla ghost population and the common ancestor of the eastern lowland gorillas and the mountain gorillas. The researcher Martin Kuhlwilm describes, “Up to 3 % of the genome these dayss eastern gorillas consists of remains of genes from this ghost population, which separated from the common ancestors of all gorillas more than 3 million years ago.” And he continues, “On the other hand, we were not able to identify any of these DNA segments in the western gorillas.”
Gene circulation from ghost population might affect gene functions
The international group was able to impress that the genetic input of already extinct forefathers is not only of interest in evolutionary history but can likewise have functional results on contemporary types.
They showed this with an example: The researchers found that a gene encoding a bitter taste receptor was presented from the ghost population into todays eastern lowland gorillas and mountain gorillas– and might have afterward been under favorable selection. This comes in convenient for todays animals, because this sort of taste receptors probably helps avoid consuming poisonous (and bitter-tasting) food.
Another interesting result from the analysis is that the eastern gorillas sustain an extremely percentage of DNA from the ghost population on their X chromosome. Therefore, it appears to be subject to unfavorable choice, which can also be observed in humans and other types. One possible factor for this is that this chromosome exists only in one copy in male individuals, unlike the other chromosomes, and this is why hazardous anomalies may have a stronger effect.
Tomas Marques-Bonet, likewise a professor of Genetics at the Department of Medicine and Life Sciences (MELIS) at UPF says, “Our study provides us a much better insight into the evolutionary history of gorillas and provides a valuable contribution to help us much better comprehend which results gene streams from extinct populations can have on existing populations.” “Evolutionary genetics is important,” adds Harvinder Pawar, very first author of the study, “so that we can discover more about what differentiates us humans from other apes.”
Reference: “Ghost admixture in eastern gorillas” by Harvinder Pawar, Aigerim Rymbekova, Sebastian Cuadros-Espinoza, Xin Huang, Marc de Manuel, Tom van der Valk, Irene Lobon, Marina Alvarez-Estape, Marc Haber, Olga Dolgova, Sojung Han, Paula Esteller-Cucala, David Juan, Qasim Ayub, Ruben Bautista, Joanna L. Kelley, Omar E. Cornejo, Oscar Lao, Aida M. Andrés, Katerina Guschanski, Benard Ssebide, Mike Cranfield, Chris Tyler-Smith, Yali Xue, Javier Prado-Martinez, Tomas Marques-Bonet and Martin Kuhlwilm, 27 July 2023, Nature Ecology & & Evolution.DOI: 10.1038/ s41559-023-02145-2.
There are few comparable studies addressing this question in fantastic apes, especially gorillas, due to the fact that there are only a few fossils of our close living family members, unlike the Homo sapiens, from which ancient DNA could be extracted for analysis. The genomes of individuals living today are the only method to reconstruct their evolutionary history, which is of particular value, because gorillas are threatened with extinction in the wild.
Ingenious analytical methods consisting of the integration of neural networks revealed a surprising result: 40,000 years earlier, genes were exchanged in between a now-extinct gorilla ghost population and the common forefather of the eastern lowland gorillas and the mountain gorillas. And he continues, “On the other hand, we were not able to recognize any of these DNA sectors in the western gorillas.”
Another interesting result from the analysis is that the eastern gorillas sustain a very little quantity of DNA from the ghost population on their X chromosome.