erged from the western rainforest population about 4,000 years ago —while still remaining closely related members of the same subspecies. (In contrast, this subspecies as a whole diverged from the Central Chimpanzee subspecies (Pan troglodytes troglodytes), whose populations live in Congo River Basin forests south of the Sanaga River, about 200,000 years ago or more.)
In subsequent modeling in a second paper, Mitchell and colleagues concluded that in the Nigeria-Cameroon chimpanzee, a significant amount of genetic difference could come from adaptation to different environments.
In short, these chimps have changed in distinct, genetically noticeable ways, to their lives in different habitats.
Environments Threatened by Climate Change
Yet the habitats these chimps rely on may be particularly threatened, the team’s analysis has showed.
“We were surprised to see that the Nigeria-Cameroon chimpanzees living in the savanna-woodland habitat of central Cameroon are under the most immediate threat of climate change, and may completely lose their habitat within our lifetime,” said Sesink Clee.
Drexel University researchers Paul Sesink Clee (seated) and Matthew Mitchell (standing, center) analyzing climate data from a field site with researchers from Ebo Forest Research Project. Credit Mary Katherine Gonder
He and colleagues reached this conclusion based on combining detailed chimpanzee location data with the environmental characteristics of these locations. They then predicted how these habitats would change under climate change scenarios for years 2020, 2050, and 2080. The scenarios were provided by the UN’s Intergovernmental Panel on Climate Change and considered a varying range of factors including use of fossil and non-fossil fuels, human population growth, and environmental protection efforts.
While the team predicted little change in the mountainous rainforest habitat, the ecotone habitat of the second population was predicted to decline quickly under all scenarios by the year 2020 and could disappear almost entirely under the worst case scenario by 2080. With roughly half of the 6,000 Nigeria-Cameroon chimpanzees existing in the ecotone habitat of central Cameroon, the results suggest that this subspecies of chimpanzee is particularly vulnerable to climate change.
The authors note that their models may be something of a worst-case scenario for climate change because they do not take into account the potential for these chimpanzee populations to adapt to the changes brought about by climate change, or to migrate to new areas with optimal conditions. On the other hand, chimpanzees continue to face other threats of habitat loss to human land uses, as well as illegal hunting.
“We know very little about Nigeria-Cameroon chimpanzees in the wild,” said Gonder. “But everything we have learned about them suggests that Cameroon is a particularly vital location for preserving the diversity found within the species. The governments of Cameroon and Nigeria have made important strides in the last five years to save their chimpanzee remaining populations. The papers published this week in BMC Evolutionary Biology will boost these efforts by providing a solid foundation for policy makers in these countries to make stronger arguments for additional protection in places, such as central Cameroon, which have often been overlooked in ape conservation planning activities.”
Paul Sesink Clee (left) and Matthew Mitchell (right) in Cameroon
For more about the process of the research described above, see the blog post by Gonder, Mitchell and Sesink Clee on the BMC Series Blog.
For more information about Drexel University’s ongoing research projects in Central Africa, please visit: caballiance.org and bioko.org
For more information on the Nigeria-Cameroon chimpanzee or to read the IUCN conservation action plan, please visit: ellioti.org
For more information on the Gonder Lab at Drexel University, please visit: pages.drexel.edu
Portions of this article were adapted with permission from a press release prepared by BMC Evolutionary Biology.
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