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Temperature regulation and oxygen consumption in the developing macropod marsupial Setonix brachyurus
The Journal of Physiology
|August 1, 1977
Summary
Young marsupial joeys cannot regulate body temperature until 166 days old. Developing high oxygen consumption is key for thermoregulation in cooler environments, while pouch conditions necessitate cooling mechanisms.
Area of Science:
- Physiology
- Developmental Biology
- Thermoregulation
Background:
- Mammalian joeys, particularly marsupials, often exhibit underdeveloped thermoregulation at birth.
- Understanding the ontogeny of thermoregulation is crucial for species survival and conservation efforts.
Purpose of the Study:
- To investigate the developmental timeline of thermoregulation in marsupial joeys.
- To identify the critical physiological changes enabling homeothermy in young marsupials.
Main Methods:
- Colonic temperatures of joeys of varying ages were measured at ambient temperatures (17.5-24°C).
- Oxygen consumption rates were assessed in response to cooling.
- Body temperature responses were monitored in a high-humidity, pouch-temperature environment.
Main Results:
- Joeys younger than 166 days showed declining colonic temperatures near ambient levels.
- The ability to sustain high oxygen consumption for thermogenesis developed between 144-169 days.
- Joeys over 130 days experienced lethal hyperthermia in a simulated pouch environment, indicating a lack of effective cooling.
Conclusions:
- Marsupial joeys gain the ability to maintain stable body temperature around 166 days of age.
- Development of high oxygen consumption is a prerequisite for thermoregulation in cool conditions.
- Early-stage joeys require efficient heat dissipation mechanisms within the pouch to prevent hyperthermia.