Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Moonstruck primates: Owl monkeys need moonlight as much as a biological clock for nocturnal activity

06.09.2010
An international collaboration led by a University of Pennsylvania anthropologist has shown that environmental factors, like temperature and light, play as much of a role in the activity of traditionally nocturnal monkeys as the circadian rhythm that regulates periods of sleep and wakefulness.

The study also indicates that when the senses relay information on these environmental factors, it can influence daily activity and, in the case of a particular monkey species, may have even produced evolutionary change. It is possible, according to the study results, that changes in sensitivity to specific environmental stimuli may have been an essential key for evolutionary switches between diurnal and nocturnal habits in primates. The study also provides data to better understand all life cycles.

Researchers set out to examine the hypothesis that masking, the chronobiology term for the stimulation or inhibition of activity, was largely caused by changing environmental factors that affected the Azara's owl monkeys' internal timing system, or synchronized circadian rhythm. Put simply, changes in temperature and light make Azara's owl monkeys the only anthropoid primate (monkeys, apes and humans) with a propensity for both early bird and night owl behavior.

The observational nature of field studies has generally limited science's understanding of the mechanisms responsible for the change in activity patterns of these species, whose behavior traditionally takes place in the dimmest of light. Researchers monitored the activity of these wild owl monkeys continually for as long as 18 months using actimeter collars fitted to them.

The results represent the first long-term study of wild primates providing direct evidence for environmental masking, according to researchers.

The data indicate that, although regular daytime activity is represented by the output of a circadian clock, nocturnality is the result of fine-tuned masking of circadian rhythmicity by environmental light and temperature.

Specifically, date showed that nocturnal activity was more consolidated during the relatively warmer months of September to March than during the colder months of April to August, when temperatures in the Argentine province of Formosa regularly fall below 10ºC. Throughout the year, nocturnal activity was higher during full-moon nights than during new-moon ones, and these peaks of nocturnal activity were consistently followed by mornings of low activity. Conversely, new-moon nights were usually followed by mornings of higher diurnal activity than mornings following full-moon nights.

"The behavioral outcome for these owl monkeys is nocturnal activity maximized during relatively warm, moonlit nights," said Eduardo Fernández-Duque, lead investigator and an assistant professor in the Department of Anthropology in Penn's School of Art and Sciences.

"While laboratory studies have pointed to the importance of masking in determining the environmental factors that cause animals to switch from nocturnal activity patterns to diurnal ones or vice versa, our study underscores the importance of masking in determining the daily activity patterns of animals living in the wild. It also suggests that moonlight is a key adaptation for the exploitation of the nocturnal niche by primates," he said.

Conclusive evidence for the direct masking effect of light was provided when three full lunar eclipses completely shadowed moonlight, coinciding with diminished monkey activity. Temperature also negatively masked locomotor activity, and this masking was manifested even under optimal light conditions.

"If there was a biological clock that they were depending on to regulate this activity, you could expect the activity to continue even in the absence of lunar light," said Horacio de la Iglesia of the Department of Biology at the University of Washington.

Primates — even humans — conduct their daily tasks in patterns ranging from nocturnality to diurnality, with a few species showing activity both during day and night. Among anthropoids (monkeys, apes and humans), nocturnality is only present in the Central and South American owl monkey genus Aotus. But unlike other tropical Aotus species, the Azara's owl monkeys (A. azarai) of the subtropics, and this study, have actually switched their activity pattern from strict nocturnality to one that also includes regular daytime activity. The phenomenon led researchers to question the causes of such a behavioral change.

"Harsher climate, food availability and the lack of predators or daytime competition have all been proposed as factors favoring evolutionary switches in primate activity patterns," Fernández-Duque said.

"The lunar day has not been a stable force as much as the solar day to evolutionarily select for a clock," de la Iglesia said. "We still have to prove it in the lab, but the evidence in this paper points to a lack of a lunar biological clock."

The article appears in the current issue of the journal PLoS ONE.

The study was conducted by Fernández-Duque, de la Iglesia and Hans G. Erkert of the University of Tübingen.

The research was funded by the Zoological Society of San Diego, Leakey Foundation, Wenner-Gren Foundation and National Geographic Society. It was authorized by the Ministerio de la Producción, Subsecretaría de Ecología y Recursos Naturales and Dirección de Fauna from Formosa Province.

Jordan Reese | EurekAlert!
Further information:
http://www.upenn.edu

More articles from Studies and Analyses:

nachricht Amputees can learn to control a robotic arm with their minds
28.11.2017 | University of Chicago Medical Center

nachricht The importance of biodiversity in forests could increase due to climate change
17.11.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Long-lived storage of a photonic qubit for worldwide teleportation

12.12.2017 | Physics and Astronomy

Multi-year submarine-canyon study challenges textbook theories about turbidity currents

12.12.2017 | Earth Sciences

Electromagnetic water cloak eliminates drag and wake

12.12.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>