Avian thermoregulation in the heat: efficient evaporative cooling allows for extreme heat tolerance in four southern hemisphere columbids
| Autor: | Eric Krabbe Smith, Ben Smit, Blair O. Wolf, William A. Talbot, Maxine C. Whitfield, Alexander R. Gerson, Andrew E. McKechnie, Todd J. McWhorter |
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| Rok vydání: | 2016 |
| Předmět: |
030110 physiology
0301 basic medicine Thermotolerance Hot Temperature Physiology Aquatic Science Ocyphaps lophotes 03 medical and health sciences South Africa Animal science Animals Columbidae Molecular Biology Ecology Evolution Behavior and Systematics Namaqua dove biology Streptopelia capicola Air Australia Thermoregulation biology.organism_classification Laughing dove Water Loss Insensible Insect Science Basal metabolic rate Animal Science and Zoology Basal Metabolism Evaporative cooler Body Temperature Regulation |
| Zdroj: | The Journal of experimental biology. 219(Pt 14) |
| ISSN: | 1477-9145 |
| Popis: | Birds show phylogenetic variation in the relative importance of respiratory versus cutaneous evaporation, but the consequences for heat tolerance and evaporative cooling capacity remain unclear. We measured evaporative water loss (EWL), resting metabolic rate (RMR) and body temperature (Tb) in four arid-zone columbids from southern African [Namaqua dove (Oena capensis, ∼37 g), laughing dove (Spilopelia senegalensis, ∼89 g) and Cape turtle dove (Streptopelia capicola, ∼148 g)] and Australia [crested pigeon (Ocyphaps lophotes), ∼186 g] at air temperatures (Ta) of up to 62°C. There was no clear relationship between body mass and maximum Ta tolerated during acute heat exposure. Maximum Tb at very highest Ta was 43.1±1.0°C, 43.7±0.8°C, 44.7±0.3°C and 44.3±0.8°C in Namaqua doves, laughing doves, Cape turtle doves and crested pigeons, respectively. In all four species, RMR increased significantly at Ta above thermoneutrality, but the increases were relatively modest with RMR at Ta=56°C, 32%, 60%, 99% and 11% higher, respectively, than at Ta=35°C. At the highest Ta values reached, evaporative heat loss was equivalent to 466%, 227%, 230% and 275% of metabolic heat production. The maximum ratio of evaporative heat loss to metabolic production observed in Namaqua doves, 4.66, exceeds by a substantial margin previous values reported for birds. Our results support the notion that cutaneous evaporation provides a highly efficient mechanism of heat dissipation and an enhanced ability to tolerate extremely high Ta. |
| Databáze: | OpenAIRE |
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