Anatomical and neurochemical peculiarities of the pika retina: basis for lack of circadian rhythm of core temperature

Luo, Zong-Wei; Kosaka, Mitsuo; Othman, Timothy; Piad, James N.C; Cao, Yu; Lee, Jeong‐Beom; Matsumoto, Takaaki; Ohwatari, Nobu; Ichinose, Akitoyo; Mori, Keiji; Tonosaki, Akira

doi:10.1016/s0304-3940(98)00896-9

Cited by 2 publications

(2 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although most small mammals show diurnal patterns of body temperature change, this pattern of body temperature change was unexpected because previous laboratory studies have emphasized that pikas lack such a diurnal cycle (83). When we kept some implanted pikas in the laboratory for a short period, we also noted there was no diurnal cycle in their body temperatures (SI Appendix, Fig.…”

Section: Ecologymentioning

confidence: 66%

“…Our data therefore suggest the absence of a diurnal body temperature cycle in pikas (as described in ref. 83) is probably an artifact of captivity. The cycle of temperature appeared to be regulated in relation to the ambient temperature (R 2 of relation between body and ambient temperature for day and for night was 0.464 and 0.278, respectively) and, hence, putative energy demands for thermoregulation.…”

Section: Ecologymentioning

confidence: 99%

See 1 more Smart Citation

Surviving winter on the Qinghai-Tibetan Plateau: Pikas suppress energy demands and exploit yak feces to survive winter

Speakman

Chi

Ołdakowski

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The Qinghai-Tibetan Plateau, with low precipitation, low oxygen partial pressure, and temperatures routinely dropping below −30 °C in winter, presents several physiological challenges to its fauna. Yet it is home to many endemic mammalian species, including the plateau pika (Ochotona curzoniae). How these small animals that are incapable of hibernation survive the winter is an enigma. Measurements of daily energy expenditure (DEE) using the doubly labeled water method show that pikas suppress their DEE during winter. At the same body weight, pikas in winter expend 29.7% less than in summer, despite ambient temperatures being approximately 25 °C lower. Combined with resting metabolic rates (RMRs), this gives them an exceptionally low metabolic scope in winter (DEE/RMRt = 1.60 ± 0.30; RMRt is resting metabolic rate at thermoneutrality). Using implanted body temperature loggers and filming in the wild, we show that this is achieved by reducing body temperature and physical activity. Thyroid hormone (T3 and T4) measurements indicate this metabolic suppression is probably mediated via the thyroid axis. Winter activity was lower at sites where domestic yak (Bos grunniens) densities were higher. Pikas supplement their food intake at these sites by eating yak feces, demonstrated by direct observation, identification of yak DNA in pika stomach contents, and greater convergence in the yak/pika microbiotas in winter. This interspecific coprophagy allows pikas to thrive where yak are abundant and partially explains why pika densities are higher where domestic yak, their supposed direct competitors for food, are more abundant.

show abstract

Section: Ecologymentioning

confidence: 66%

Section: Ecologymentioning

confidence: 99%