Most Complete Bonobo Genome Assembly Provides Clues on Great Ape Evolution

A large collaboration of scientists has constructed a new bonobo genome assembly with a multiplatform approach that sequenced and identified more than 98% of the gene, which closed 99% of the gaps in great ape evolution.

Phys.org reported that this high-quality bonobo genome assembly enabled scientists to more accurately compare the bonobo genome to other great apes, such as chimpanzees, gorilla, and orangutan, as well as modern humans.

Comparing higher-quality genomes could help understand genetic changes that set humans apart from great ape species, the closest living species of modern humans.

What Sets Humans Apart From Great Apes?

Genome sciences professor Evan Eichler of the University of Washington said that genetic changes that occurred throughout the evolution of great apes could have been encoded in the genomes of modern humans.

Bonobos and chimpanzees are two great ape species that are closely related to humans who share between 98% to 99% of the same DNA with Homo sapiens, The Atlantic Times reported.

Previous bonobo genomes still have gaps that Eichler described as similar to Swiss cheese with 108,000 gaps. But through an effort that started four years ago, which Eichler calls a labor of love, scientists have completely annotated 98% of the genes in the bonobo genome and closed 99% of the gaps.

The team compared the genomes of bonobo to those of great apes and humans and found a rapid and complex genetic evolution. They identified numerous genes that are only found in either bonobo and chimpanzee who diverged into different species 1.7 million years ago and has 0.4% genetic differences.

Furthermore, they found many parts of the genome in which humans are more similar to either bonobo and chimpanzees than either of the two have in common. This is called incomplete lineage sorting, which is unusual because humans have diverged from the lineage about seven to 13 million years ago.

But through this phenomenon, it says that a species may not share some genomes with closely related species while sharing it more with a distant relative.

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Increasing Incomplete Lineage Sorting (ILS)

Stretching back further in the evolutionary history, about 15 million years ago, the team included genome data from orangutans and gorillas to increase the incomplete lineage sorting estimates for hominid genomes. According to Genome Web, the team estimated around 36.5%of the human genome may be marked with ILS.

One-quarter of the genes found to be subject to incomplete lineage sorting are those associated with immune response and cell growth that could hold a past and present evolutionary benefit.

Phys.org reported that the new genome assembly is named after Mhudiblu, the female great ape whose DNA was sequenced. The researchers estimated that the assembly accurately sequences the genome by about 99.97% to 99.99% and closes 99.5% of the gaps from the previous bonobo assembly.

Eichler believes that there are further things to discover on the bonobo genome that has radically changed throughout the great ape evolution that is crucial for the ape's conservation.

Their study, entitled "A high-quality bonobo genome refines the analysis of hominid evolution," was published on May 5 in the journal Nature.