Gauging how warmer climate impacts a particular species can be a challenging task, but researchers from the Max Planck Institute for Evolutionary Anthropology say that they’ve unearthed indisputable evidence for heat stress in Savana-based chimpanzees.
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Reporting in the journal Frontiers in Ecology and Evolution, the researchers describe how chimpanzee urine sample analyses exposed hormonal imbalances consistent with both dehydration and increased heat stress.
These hormones included creatinine, which denotes how dehydrated the animal is, and cortisol, which indicates a stress response. Together, the excess presence of these hormones paints an eerie picture for Savana-based chimpanzees and their lifestyle.
"The weather at Fongoli can be brutal, where the average maximum temperature is over 37º Celsius (98.6º Fahrenheit), and periods go by each year when rain doesn't fall for over seven months," explained study lead author Erin Wessling.
The study also examined the c-peptide levels of the Savana-based chimpanzees, and the results were consistent with acceptable energy levels and hydration; this would suggest that the chimpanzees have established ways of coping with the extreme Savana environment despite the challenges in doing so.
"If we are thought to have evolved in similar habitats, then this underlines the importance of adaptations for overcoming or avoiding thermoregulatory stress in our own evolutionary history," Wessling continued.
"As a next step, it would then be important to show that these stresses are not only important but also unique to these types of habitats."
To validate the findings, Wessling and her colleagues performed similar tests on chimpanzees from Tai National Park, a neighboring rainforest where conditions are a little subtler – cooler temperatures and more moisture.
Unsurprisingly, the rainforest-based chimpanzees didn’t exhibit the same cortisol levels, which means they don’t experience the same heat stress that the Savana-based chimpanzees do.
Food availability between the two different habitats also indicated curious results. While the food was more abundant for the rainforest-dwelling chimpanzees, their Savana-based counterparts developed tastes for new kinds of food so that they could meet their energy needs.
"In view of the ongoing climate change, we are now better able to understand what the consequences for the critically endangered western chimpanzee may be in the near future, with regard to increased ecological pressures and necessity to adapt flexibly, to the overall habitability of regions at the limit of their distribution and even potential range shifts," added study co-author Hjalmar Kuehl.
Future research may discern whether these characteristics are unique to chimpanzees or if other animals have their own ways of adapting to hotter climates.
Source: Max Planck Institute for Evolutionary Anthropology via Phys.org