Scientists have created the world's first wild chimp genetic map, providing a precise reconstruction of the endangered species' previous travels as well as a new tool to prevent illegal trafficking.
Kidnapped chimps—or their meat and body parts—can now be linked to their point of origin within 100 kilometres thanks to the genetic catalogue, which includes 828 individuals from across their broad African habitat.
The findings of the multi-year study were published in the journal Cell Genomics on Wednesday.
"If we can know the genetic diversity of this endangered species, and its historical demographic history," first author Claudia Fontsere of the Institute of Evolutionary Biology in Spain told AFP, "this can help develop a better conservation plan."
Thousands of chimp droppings were gathered as part of the Pan African Program in 48 locations across central and western Africa.
Fecal samples are a good technique to investigate endangered species since they enable for a large number of samples to be collected with little disturbance to the animals.
However, because they only contain minimal amounts of host DNA, they pose technological hurdles.
To get around these limitations, the researchers used a new DNA sequencing technology known as "target capture," which was first used to investigate Neanderthals whose remains had decayed over thousands of years.
This allowed scientists to find 50 percent more polymorphisms on chromosome 21 than had previously been discovered, allowing them to infer past gene flow between chimp populations and filling gaps in scientific knowledge.
Only 59 entire chimp genomes had previously been sequenced, most of which came from captivity animals with little knowledge about their origins.
Migrations that are difficult to understand
Chimpanzees, like humans, have complicated migration histories, and the new discovery enables scientists to go back 100,000 years in unprecedented depth.
"There has been a lot of disagreement over whether the four chimpanzee subspecies genuinely separated or whether there was persistent gene-flow between them," said Mimi Arandjelovic of the Max Planck Institute for Evolutionary Anthropology, one of the study's co-lead authors.
"We were able to demonstrate that the history is complex, similar to that of our own species, utilising several analysis approaches that look at extremely old and more recent variation."
The researchers discovered that the chimp subspecies have been separated in the past, but have also had periods of genetic interchange, which may explain why previous studies attempting to recreate chimp evolution have come to conflicting findings.
They observed that geographical obstacles such as lakes and rivers produced genetic barriers between subspecies and groups, as well as fresh information regarding periods when chimps and bonobos interbred.
They also confirmed a significant amount of connectedness amongst Western chimps, emphasising the importance of preserving forest links across Western Africa, according to Arandjelovic.
The genetic map, according to Fontsere, could assist track down where unlawfully trafficked chimps came from.
Despite the fact that reintroduction chimps to the wild is a difficult task due to the animals' intricate social structure, research has shown that they thrive better when placed in a refuge near their birthplace.
"It can assist law enforcement in looking at the more likely paths, and we can trace it back," Fontsere explained.
They plan to add more samples to the genetic map and, now that faecal DNA has been proven to be a viable alternative, to use it to investigate other primates.
Written by:
HASHIR BIN SHAHID.
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