By Stephen Beech
Chimps have genetically adapted to thrive in their natural habitats and avoid deadly malaria, according to a new study.
The primates are our closest living relatives, sharing more than 98% of their DNA with humans.
Scientists say that their findings can not only teach us about our own evolutionary history but also about the biology of malaria infection in humans.
Chimpanzees are classified as endangered due to habitat destruction, poaching and infectious diseases.
However, researchers say the new study, published in the journal Science, could also help conservation efforts as they suggest that climate and land use changes will likely have different impacts on different groups of chimps.
The study was conducted by an international team led by researchers from University College London.
Lead author Professor Aida Andrés, of UCL, said: “There are just a few hundred thousand chimpanzees alive, but they are found across very different landscapes from east Africa to the far west of the continent, including dense tropical rainforests and open areas of woodland and savannah.
“This makes them quite unique because except for humans, all other apes live exclusively in forests.
“We have shown that besides acquiring behavioral adaptations, different chimpanzee populations have evolved genetic differences to survive in their different local habitats.
“As chimpanzees are facing threats across their range, including environmental changes to the climate and displacement due to human pressures, it is important that their genetic diversity is conserved to maintain their resilience and ensure the long-term survival of this intelligent and fascinating species.”
To study genetic adaptation, the researchers needed to obtain DNA from the highly elusive wild chimps without disturbing them.
To do so, they used fecal samples that were collected as part of the Pan African Programme: The Cultured Chimpanzee (PanAf).
State-of-the-art lab and computational methods enabled the scientists to study the chimpanzee DNA in the samples and perform the largest study of local adaptation in wild endangered mammals to date.
The team analyzed the exomes – the protein-coding part of the genome – from 828 wild chimpanzees, 388 of which were included in the final analysis, representing 30 different chimp populations from the four chimpanzee subspecies.
The research team compared the genetic information to data about the local environment each chimp population lives in, identifying genetic variants that stand out as being much more frequent in certain regions than others, and that likely confer a benefit to those carrying the genetic variant in particular habitats.
They found evidence of genetic adaptation in genes related to certain disease-causing microorganisms, known as pathogens, among the chimps living in forests, where there is a high concentration of pathogens, with the strongest evidence found in genes linked to malaria.
These include two genes that are also known to be responsible for adaptation and resistance to malaria in humans: GYPA and HBB, the latter being responsible for sickle cell anemia in humans.
The findings suggest that malaria is likely a “significant” disease for wild forest chimpanzees and that adaptation to the malaria parasite has happened, independently, through changes in the very same genes in chimps and humans.
“Finding evidence of adaptation to malaria in chimpanzees linked to the same genes that affect malaria resistance in humans is striking from an evolutionary point of view, as it suggests there may be limited ways that we can evolve resistance to the malaria parasite.”
The study suggests that chimps have also adapted to their savannah habitats, which have higher temperatures, lower rainfall and less food availability.
The researchers say that shows that studying savannah chimps may shed light on how human ancestors adapted to similar habitats millions of years ago when they first moved from the African forest to the savannah.
Co-author and PanAf co-director Dr. Hjalmar Kuehl said: “This ground-breaking study on chimpanzee local adaptations could not be accomplished without the extraordinary collaboration of an international team of scientists who worked tirelessly to collect non-invasive data, including fecal samples, from countries across the chimpanzee range.”
Co-author and PanAf co-director Dr Mimi Arandjelovic added: “We further welcome everyone interested in our research to contribute as community scientists at ChimpandSee.org, where one can help annotate videos collected alongside the genetic samples from across the chimpanzee range.”
