title: Arabian Oryx (Oryx leucoryx) Respond to Increased Ambient Temperatures with a Seasonal Shift in the Timing of Their Daily Inactivity Patterns.
abstract: The Arabian oryx inhabits an environment where summer ambient temperatures can exceed 40 °C for extended periods of time. While the oryx uses a suite of adaptations that aid survival, the effects of this extreme environment on inactivity are unknown. To determine how the oryx manages inactivity seasonally, we measured the daily rhythm of body temperature and used fine-grain actigraphy, in 10 animals, to reveal when the animals were inactive in relation to ambient temperature and photoperiod. We demonstrate that during the cooler winter months, the oryx was inactive during the cooler parts of the 24-h day (predawn hours), showing a nighttime (nocturnal) inactivity pattern. In contrast, in the warmer summer months, the oryx displayed a bimodal inactivity pattern, with major inactivity bouts (those greater than 1 h) occurring equally during both the coolest part of the night (predawn hours) and the warmest part of the day (afternoon hours). Of note, the timing of the daily rhythm of body temperature did not vary seasonally, although the amplitude did change, leading to a seasonal alteration in the phase relationship between inactivity and the body temperature rhythm. Because during periods of inactivity the oryx were presumably asleep for much of the time, we speculate that the daytime shift in inactivity may allow the oryx to take advantage of the thermoregulatory physiology of sleep, which likely occurs when the animal is inactive for more than 1 h, to mitigate environmentally induced increases in body temperature.
authors.affiliation: *School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa.
authors.forename: Joshua G
authors.initials: JG
authors.lastname: Davimes
authors.affiliation: Department of Zoology, KSU Mammals Research Chair, College of Science, King Saud University, Saudi Arabia Saudi Wildlife Authority, Saudi Arabia.
authors.forename: Abdulaziz N
authors.initials: AN
authors.lastname: Alagaili
authors.affiliation: *School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa.
authors.forename: Nadine
authors.initials: N
authors.lastname: Gravett
authors.affiliation: Centre for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, Denmark.
authors.forename: Mads F
authors.initials: MF
authors.lastname: Bertelsen
authors.affiliation: Department of Zoology, KSU Mammals Research Chair, College of Science, King Saud University, Saudi Arabia.
authors.forename: Osama B
authors.initials: OB
authors.lastname: Mohammed
authors.affiliation: Prince Saud Alfaisal Wildlife Research Center, Taif, Saudi Arabia.
authors.forename: Khairy
authors.initials: K
authors.lastname: Ismail
authors.affiliation: Department of Zoology, KSU Mammals Research Chair, College of Science, King Saud University, Saudi Arabia University of Pretoria, Pretoria, South Africa.
authors.forename: Nigel C
authors.initials: NC
authors.lastname: Bennett
authors.affiliation: *School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, Republic of South Africa Paul.Manger@wits.ac.za.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Manger
mesh_terms: D056044:Actigraphy; D000204:Activity Cycles; D000222:Adaptation, Physiological; D000818:Animals; D000866:Antelopes / Q000502:physiology*; D001831:Body Temperature; D001833:Body Temperature Regulation; D002940:Circadian Rhythm; D003889:Desert Climate; D005334:Fever; D017440:Photoperiod; D012621:Seasons; D012890:Sleep; D013696:Temperature
keywords: Arabian oryx; circadian rhythms; masking; seasonality; sleep; temperature