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TOTAL EVAPORATIVE WATER LOSS AT DIFFERENT AMBIENT TEMPERATURES IN BIRDS: RELATION TO METABOLIC RATE AND BODY MASSстатья Тезисы
- Автор: Gavrilov V.M.
- Журнал: Principles of the ecology
- Том: 5
- Номер: 3(19)
- Год издания: 2016
- Первая страница: 40
- Последняя страница: 40
- Аннотация: TOTAL EVAPORATIVE WATER LOSS AT DIFFERENT AMBIENT TEMPERATURES IN BIRDS: RELATION TO METABOLIC RATE AND BODY MASS Gavrilov V. M. Department of Vertebrate Zoology and Zvenigorod Biological Station, M.V. Lomonosov Moscow State University, Moscow 119991, Russia e-mail: vmgavrilov@mail.ru Correlates of basal metabolic rate (BMR) and total evaporative water loss (TEWL) was studied in captive birds using literature data (Gavrilov, Dolnik, 1985, Gavrilov 1995, 1997, 2014, 2015; Williams, 1996; McNab, 2009, 2015) and original data from more than 60 species of Passerine birds and 30 species of Non- passerine birds during summer and winter seasons and in different ambient temperatures. After combining the data for 102 species of birds from Table 1 obtained by Williams (Williams 1996) and my data for 157 species of birds at thermally neutral temperatures (mostly 25oC) to improve the statistical significance, the relationship between TEWL and body mass is: TEWL25oC Aves=0.28m0.70, R2=0.92, where TEWL is expressed as g H2O/day and m is body mass (g). McNab (2009) showed that the power of body mass describing BMR in birds is 0.652±0.007. The power of body mass describing TEWL in birds is 0.701±0.007 which is 0.05 greater than in BMR. The relation in the equation between body size and TEWL is higher than between body size and BMR. If the dichotomy between passerines and nonpasserines is added, the power describing BMR becomes 0.721±0.009, or 0.705±0.010 and the power of body mass describing TEWL in Passeriformes and Non-Passeriformes is 0.754 which is 0.05 greater than in BMR. The relationship between TEWL and body mass shows that the ratio of TEWL to body mass in passerine birds is higher than in Non-passerine birds’ at all ambient temperatures (0°C, Tlc, 25°C, and Tuc). The dependence of water loss from the body mass at different TA varies by the same manner as the correlation between evaporative and nonevaporative heat loss. In Passeriformes, TEWL is approximately 25–40% higher than in non-passerines (particularly at high TA), which is consistent with the ratio of their BMR levels. Thus, a large expenditure of evaporative water determines the cost of the advantages of BMR increase and results in a higher energetic capability. This expenditure increased with the body size in Passeriformes due to the forced evaporative heat loss and showed virtually no increase in Non-Passeriformes. In Non-Passeriformes, there were nearly equal increases in the evaporative water loss and metabolic rate in the summer and in the winter, suggesting that this group maintained heat balance even at the upper critical temperature, which is the ambient temperature at which additional mechanisms are insufficient to balance out the invariable BMR heat production. This requirement imposes strong limitations on the range of sizes in Passeriformes. A high basal metabolic rate (BMR) in Passeriformes includes not only net benefits but also its maintenance that requires a definite cost. These findings suggest that the high level of basal metabolic rate in Passeriformes in comparison to Non-Passeriformes determines the necessity for them to utilize con¬siderably greater amounts of water for evaporation to maintain a sufficient heat balance at high ambi¬ent temperatures. This requirement imposes strong limitations on the range of sizes in this group, and despite the consider¬able ecological and energy advantages of such high BMR levels, this pattern is not often found in other groups of endothermic animals. A considerable evaporative water loss reflects the cost of the higher BMR and energy capacities of Passerines in comparison with Non-passerines and other orders of endothermic animals. As shown in the previous study (Gavrilov, 1997, 2014), an increase in BMR results in an increase in the maximal existence metabolic rate and potential productive energy, that expands the ecological capability. These changes confer many benefits but minimize the optimal sizes. Analysis of the allometric regressions for the energetic parameters shows that Passerines with a body mass ranging from 5–150 g have significantly higher productive energy than Non-Passeriformes (Gavrilov, 1997, 2014). About 80% of Passeriformes species have body mass in this range. Thus, a large expenditure of evaporative water is the cost of the higher BMR in Passeriformes than in Non-Passeriformes.
- Добавил в систему: Гаврилов Валерий Михайлович