de Heij Maaike E, van der Graaf Alexandra J, Hafner Dennis, Tinbergen Joost M
Animal Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, 9750 AA, Haren, The Netherlands.
J Exp Biol. 2007 Jun;210(Pt 11):2006-12. doi: 10.1242/jeb.001420.
To study the energetic costs of incubation in relation to clutch size, clutch sizes were manipulated and the metabolic rate of female great tits, Parus major (Linnaeus), during nocturnal incubation (MR(inc)) was measured using mobile oxygen analysers. Individuals were measured on consecutive nights while incubating their own or manipulated clutches. The experiment was performed under field conditions in order to place possible effects of clutch size manipulation within the context of other factors explaining variation in MR(inc). Females spent more energy when incubating enlarged clutches as compared with controls (6-10% more energy for three additional eggs) but did not spend significantly less energy when incubating reduced clutches. MR(inc) was strongly negatively related to ambient temperature. The effect of clutch enlargement is consistent with previous studies whereas the absence of an effect of clutch reduction is not. The small effect of clutch enlargement on MR(inc) highlights the need for further studies to include measurements of daily energy expenditure in order to judge how important energy expenditure can be in explaining fitness consequences of incubating experimentally enlarged clutches.
为了研究与窝卵数相关的孵卵能量消耗，对窝卵数进行了操控，并使用便携式氧气分析仪测量了雌性大山雀（Parus major，林奈）在夜间孵卵期间的代谢率（MR(inc)）。在个体孵育自己的或经操控的窝卵数时，连续多晚对其进行测量。该实验在野外条件下进行，以便将窝卵数操控的可能影响置于解释MR(inc)变化的其他因素背景中。与对照组相比，雌性大山雀在孵育增大的窝卵数时消耗了更多能量（额外三个卵多消耗6 - 10%的能量），但在孵育减少的窝卵数时消耗的能量并没有显著减少。MR(inc)与环境温度呈强烈负相关。窝卵数增大的影响与先前的研究一致，而窝卵数减少没有影响则不一致。窝卵数增大对MR(inc)的微小影响凸显了进一步研究的必要性，即需要纳入每日能量消耗的测量，以便判断能量消耗在解释孵育实验性增大的窝卵数对适合度的影响方面有多重要。
