Spring is coming to North America and scientists are quietly excited. Tiny dwarf lemurs are waking up after months of hibernation, the first time these thick-tailed furry animals have entered a long hibernation in captivity.
New research, which recreated seasonal conditions to induce captive dwarf lemurs into hibernation just as their wild relatives do in western Madagascar, suggests that these animals may revert to their wild hibernating forms after decades of breeding in captivity.
“We have been able to replicate their wild conditions well enough that they can replicate their [hibernation] patterns, “said Erin Ehmke, a primate biologist at the Duke Lemur Center, where the study was conducted.
The study findings should not only help improve the care of dwarf lemurs in captivity, but also provide scientists with new ways to study the biological tricks that hibernate animals use to resist environmental extremes.
Fat-tailed dwarf lemurs are master hibernators, spending up to seven months hibernating each year depending on conditions. It is an extreme survival tactic used by many mammals for 250 million years.
Dwarf lemurs, which use fat reserves in their tails to withstand the Madagascar winter, are actually our closest hibernating primate relative. To save energy in hibernation, its heart rate nearly stabilizes, its body temperature plummets, and its breathing slows to the point where scientists have observed a hibernating lemur spend 21 minutes between breaths.
Studying hibernating animals is more than an envious curiosity for scientists, as it could one day improve human health. Although it remains in the realm of science fiction for now, researchers are looking into the science of hibernation to find ways to help people survive long-distance space flights, make surgery safer, and possibly even prevent disease. .
In this study, the research team monitored eight dwarf lemurs, descendants of some wild animals brought to the Duke Lemur Center decades ago, during an artificial winter of months to see if these animals could hibernate in a similar way to their wild counterparts.
“Hibernation is literally in their DNA,” said Marina Blanco, a primate biologist at Duke University.
However, despite the best efforts to care for captive animals, they tend to behave differently from their wild friends, especially when it comes to hibernation, something that has been known to scientists for quite some time and is probably due to unnatural conditions in climate controlled zoo habitats with abundant food.
Studies have shown that captive dwarf lemurs, for example, fall into much shorter episodes of shallow hibernation, called torpor, than wild lemurs, with these energy-saving dreams rarely lasting more than 24 hours in captivity.
Whether this is just a temporary disruption to hibernation patterns or because captive lemurs have lost the physiological ability to hibernate remains a mystery.
The researchers showed that dwarf lemurs are capable of hibernating for months in captivity, supporting the idea that hibernation is biologically programmed in these animals and can be reactivated under the right conditions.
Before sheltering, the animals were equipped with radio transmitters to measure their heart rate and skin temperature, and were housed in temperature-controlled enclosures with wooden boxes designed to mimic tree hollows.
The researchers gradually adjusted the lights to coincide with the short winter hours in Madagascar, lowered the thermostat dial to 50 degrees Fahrenheit (10 degrees Celsius) and limited the animals’ food, then watched and waited.
From October to February, lemurs spent nearly three-quarters of their time in metabolic slow motion: huddled, cool to the touch, barely moving or breathing for up to 11 days straight, showing little interest in food.
Surprisingly, few studies before this one have experimented with restricting food to captive animals, even though hibernation is an extreme energy-saving strategy that animals use to survive when food is scarce.
“That males fed more times, expressed short episodes of lethargy more frequently, and were lethargic for fewer hours overall than females (although our sample size is too small to be conclusive) suggests[s] that eating may have affected the dynamics of lethargy to some extent, “the researchers wrote in their methods paper.
The lemurs, now waking from their months-long slumber, look healthy, the researchers reported, with the animals’ heart rates rebounding from 8 beats per minute (bpm) to around 200 bpm, and with it, their appetite.
With the animals recovering well, the researchers are looking to plan more studies in the run-up to winter next year, as long-lived lemurs may also harbor secrets to aging well.
“Until now, if you wanted to study hibernation in these primates, you had to go to Madagascar to find them on the spot,” Blanco said. “Now we can study hibernation here [in captivity] and follow up more closely. “
The research was published in Scientific reports.