title: Partitioning of evaporative water loss in white-winged doves: plasticity in response to short-term thermal acclimation.
abstract: We investigated changes in the relative contributions of respiratory evaporative water loss (REWL) and cutaneous evaporative water loss (CEWL) to total evaporative water loss (TEWL) in response to short-term thermal acclimation in western white-winged doves Zenaida asiatica mearnsii. We measured REWL, CEWL, oxygen consumption and carbon dioxide production in a partitioned chamber using flow-through respirometry. In doves housed for 2-4 weeks in a room heated to ca. 43 degrees C during the day, TEWL increased from 5.5+/-1.3 mg g(-1) h(-1) at an air temperature (T(a)) of 35 degrees C to 19.3+/-2.5 mg g(-1) h(-1) at T(a)=45 degrees C. In doves housed at room temperature for the same period, TEWL increased from 4.6+/-1.1 mg g(-1) h(-1) at T(a)=35 degrees C to 16.1+/-4.6 mg g(-1) h(-1) at T(a)=45 degrees C. The CEWL of heat-acclimated doves increased from 3.6+/-1.2 mg g(-1) h(-1) (64% of TEWL) at 35 degrees C to 15.0+/-2.1 mg g(-1) h(-1) (78% of TEWL) at T(a)=45 degrees C. Cool-acclimated doves exhibited more modest increases in CEWL, from 2.7+/-0.7 mg g(-1) h(-1) at T(a)=35 degrees C to 7.8+/-3.4 mg g(-1) h(-1) at T(a)=45 degrees C, with the contribution of CEWL to TEWL averaging 53% over this T(a) range. Cool-acclimated doves became mildly hyperthermic (body temperature T(b)=42.9+/-0.4 degrees C) and expended 35% more energy relative to heat-acclimated doves (T(b)=41.9+/-0.6 degrees C) at T(a)=45 degrees C, even though TEWL in the two groups was similar. In each of the two groups, metabolic rate did not vary with T(a), and averaged 7.1+/-0.5 mW g(-1) in cool-acclimated doves and 6.3+/-0.8 mW g(-1) in heat-acclimated doves. The differences in TEWL partitioning we observed between the two experimental groups resulted from a consistently lower skin water vapour diffusion resistance (r(v)) in the heat-acclimated doves. At T(a)=45 degrees C, r(v) in the cool-acclimated doves was 120+/-81 s cm(-1), whereas r(v) in the heat-acclimated doves was 38+/-8 s cm(-1). Our data reveal that in Z. a. mearnsii, TEWL partitioning varies in response to short-term thermal acclimation.
authors.affiliation: UNM Biology Department, MSC03-2020, 1 University of New Mexico, Albuquerque, NM 87131-0001, USA. aemckech@unm.edu
authors.forename: Andrew E
authors.initials: AE
authors.lastname: McKechnie
authors.forename: Blair O
authors.initials: BO
authors.lastname: Wolf
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D001481:Basal Metabolism; D001717:Birds / Q000502:physiology*; D001831:Body Temperature; D002245:Carbon Dioxide / Q000378:metabolism; D006358:Hot Temperature; D010101:Oxygen Consumption / Q000502:physiology; D012119:Respiration; D012879:Skin Physiological Phenomena; D014870:Water Loss, Insensible / Q000502:physiology*
chemical_list: D002245:Carbon Dioxide