Background: Evaporation is of significant ecological interest.Evaporation from an animal always results in a decrease in the temperature of the surface from which the evaporation occurs.Therefore,evaporation is a one-...Background: Evaporation is of significant ecological interest.Evaporation from an animal always results in a decrease in the temperature of the surface from which the evaporation occurs.Therefore,evaporation is a one-way transfer which causes heat loss from the organism.Biological evaporation always involves the loss of water which is a vital resource for nearly all biochemical processes.Evaporation is loss of heat via loss of body mass.Methods: The simultaneous determination of energy expenditure and loss of body mass in resting birds allows us to estimate evaporative heat loss.This method includes direct measurements of the energetic equivalent of the loss of body mass as the ratio between heat production,determined by the rate of oxygen consumption and the loss of body mass at various ambient temperatures.Results: The data indicate that evaporation was minimal at lower critical temperature and that the rate of evaporation increased at lower or higher temperatures.Obtained results indicate that passerine and non-passerine species have the ability to change their non-evaporative heat conductance the same number of times(approximately fourfold),and that their abilities in this respect are similar.Conclusions: The novelty of the study resides in the stoichiometric approach to determination of total evaporative water loss.The analysis shows that determinations by stoichiometric approach of total evaporative water loss yielded the values,which fit into the confidence intervals of all equations from literatures.The basal metabolic rate and nonevaporative thermal conductance are fundamental parameters of energetics and determine the level of physiological organization of an endothermic animal.展开更多
Studies in several songbird species have shown that treating females with the androgenic steroid hormone testoste- rone （T） can negatively affect female reproductive behaviors and breeding success. As the effects of...Studies in several songbird species have shown that treating females with the androgenic steroid hormone testoste- rone （T） can negatively affect female reproductive behaviors and breeding success. As the effects of T on females appear to be species-specific, it is not clear if similar effects of high T occur in non-songbird species. Here, we studied the effects of T supplementation on female reproductive behavior and oviposition in the budgerigar, Melopsittacus undulatus, a small monogamous parrot species with distinct sex differences in parental behavior. We experimentally increased T concentrations to male-like levels in T-treated females compared to controls and we allowed females to breed. We found no significant effects of treatment on the latency to enter the nestbox but T treatment significantly interfered with oviposition. Our results show that T-treated females were seven times less likely to produce a clutch than control females. As we found that T treatment had a strong inhibitory effect on oviposition, our results indicate that female budgerigars suffer fitness costs from male-like plasma T levels. Therefore, it may be possible that, also in non-songbird species, selection for higher T levels in males is constrained by a correlated response to selection which imposes fitness costs on females in terms of reproduction. Evaluating whether or not this is indeed the case requires further work combining different approaches to the study of the evolution of male and female testosterone levels [Current Zoology 61 （4）： 586-595, 2015].展开更多
基金the Russian Foundation for Basic Research for longterm support of my research (grants # 12-04-01288 and 16-04-00643)
文摘Background: Evaporation is of significant ecological interest.Evaporation from an animal always results in a decrease in the temperature of the surface from which the evaporation occurs.Therefore,evaporation is a one-way transfer which causes heat loss from the organism.Biological evaporation always involves the loss of water which is a vital resource for nearly all biochemical processes.Evaporation is loss of heat via loss of body mass.Methods: The simultaneous determination of energy expenditure and loss of body mass in resting birds allows us to estimate evaporative heat loss.This method includes direct measurements of the energetic equivalent of the loss of body mass as the ratio between heat production,determined by the rate of oxygen consumption and the loss of body mass at various ambient temperatures.Results: The data indicate that evaporation was minimal at lower critical temperature and that the rate of evaporation increased at lower or higher temperatures.Obtained results indicate that passerine and non-passerine species have the ability to change their non-evaporative heat conductance the same number of times(approximately fourfold),and that their abilities in this respect are similar.Conclusions: The novelty of the study resides in the stoichiometric approach to determination of total evaporative water loss.The analysis shows that determinations by stoichiometric approach of total evaporative water loss yielded the values,which fit into the confidence intervals of all equations from literatures.The basal metabolic rate and nonevaporative thermal conductance are fundamental parameters of energetics and determine the level of physiological organization of an endothermic animal.
文摘Studies in several songbird species have shown that treating females with the androgenic steroid hormone testoste- rone （T） can negatively affect female reproductive behaviors and breeding success. As the effects of T on females appear to be species-specific, it is not clear if similar effects of high T occur in non-songbird species. Here, we studied the effects of T supplementation on female reproductive behavior and oviposition in the budgerigar, Melopsittacus undulatus, a small monogamous parrot species with distinct sex differences in parental behavior. We experimentally increased T concentrations to male-like levels in T-treated females compared to controls and we allowed females to breed. We found no significant effects of treatment on the latency to enter the nestbox but T treatment significantly interfered with oviposition. Our results show that T-treated females were seven times less likely to produce a clutch than control females. As we found that T treatment had a strong inhibitory effect on oviposition, our results indicate that female budgerigars suffer fitness costs from male-like plasma T levels. Therefore, it may be possible that, also in non-songbird species, selection for higher T levels in males is constrained by a correlated response to selection which imposes fitness costs on females in terms of reproduction. Evaluating whether or not this is indeed the case requires further work combining different approaches to the study of the evolution of male and female testosterone levels [Current Zoology 61 （4）： 586-595, 2015].
