May 2, 2013
Two New Lemurs Added To List Of Hibernating Primates
Lee Rannals for redOrbit.com - Your Universe Online
In a new study in the journal Scientific Reports, scientists they have discovered that two little-known lemurs spend months hibernating as part of an adaptive survival strategy.
Until this study, the western fat-tailed dwarf lemur was the only primate known to snooze away months of seasonal dearth. The team says the Crossley's dwarf lemur and Sibree's dwarf lemur are now joining the list. According to the researchers, the two lemurs burrow into the soft, spongy rainforest floor in the eastern part of Madagascar and sleep for three to seven months underground.
The researchers hope their discovery leads to a better understanding of what sends hibernating animals into this standby mode.
"Exactly what triggers hibernation is still an open question," said lead author Marina Blanco a postdoctoral researcher at the Duke Lemur Center.
To learn more about their hibernation patterns, the team strapped the lemurs with temperature-sensitive radio collars before the start of the hibernation season, allowing them to find the lemurs' underground burrows and monitor their body temperature once hibernation began.
Western dwarf lemurs hibernate to survive during Madagascar's long dry season, a time when temperatures top 85 degrees, trees drop their leaves, and food and water become scarce. However, the eastern dwarf lemurs hibernate when winter temperatures occasionally dip below freezing.
"To the casual observer, it looks for all the world as if the animals are dead. Their bodies are cold, they are utterly still and they take a breath only once every several minutes or so," said co-author Anne Yoder, director of the Duke Lemur Center.
Western dwarf lemurs hibernate in drafty tree holes, where their body temperature fluctuates by as much as 20 degrees with the outside air. By contrast, the eastern dwarf lemurs keep their body temperatures more constant in their underground burrows.
Blanco said the research suggests that lemur hibernation may not be so different after all, adding that although they live in the tropics, they look more like temperate hibernators.
In 2011, scientists writing in the Journal of Neuroscience said they identified a hibernation-inducing signaling mechanism. They found that a condition called torpor caused oxygen consumption to fall to as low as one percent to a resting metabolic rate and core body temperature to near or below freezing temperatures.
"We show for the first time that activation of the adenosine receptors is sufficient to induce torpor in arctic ground squirrels during their hibernation season," said Tulasi Jinka, lead author of the paper.
Understanding hibernation could eventually lead to the development of a drug or therapy to save people's lives after a stroke or heart attack.