Exogenous passive heating during torpor arousal in free-ranging rock elephant shrews, <Emphasis Type="Italic">Elephantulus myurus</Emphasis> |
| |
Authors: | Nomakwezi?Mzilikazi Email author" target="_blank">Barry?G?LovegroveEmail author David?O?Ribble |
| |
Institution: | 1.School of Botany and Zoology,University of Natal,Scottsville,South Africa;2.Department of Biology,Trinity University,San Antonio,USA |
| |
Abstract: | In the laboratory rock elephant shrews (Elephantulus myurus; mean body mass 56.6 g) displayed the lowest torpor Tb min yet recorded (ca. 5°C) in a placental daily heterotherm. It was unknown whether these low Tbs were characteristic of daily heterothermy in free-ranging animals. It was also unclear how cost effective these low Tbs were since considerable energy is required to arouse from low Tbs on a daily basis. We continuously measured body temperature once every hour for 85 days in 13 free-ranging E. myurus from May to August 2001 (winter) in Weenen Game Reserve, KwaZulu-Natal, South Africa. We recorded a total of 412 torpor bouts. Free-ranging E. myurus had a high propensity for torpor with females displaying higher torpor frequency than males. The lowest Tb recorded was 7.5°C at Ta=2.7°C and the minimum torpor Tb was strongly correlated with ambient temperature. Torpor arousal was tightly coupled with ambient temperature cycles. Low torpor Tb min at low Tas was therefore cost-effective because the animals offset the high cost of arousal through exogenous passive heating. Laboratory studies under constant ambient temperatures may therefore underestimate the energetic benefits of torpor in free-ranging small mammals that inhabit regions where seasonality is moderate. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|