DuRant S E, Hopkins W A, Hepp G R
Fish and Wildlife Conservation, Virginia Tech, Blacksburg, Virginia 24061, USA.
Physiol Biochem Zool. 2011 Sep-Oct;84(5):451-7. doi: 10.1086/661749.
Recent research in birds has demonstrated that incubation temperature influences a suite of traits important for hatchling development and survival. We explored a possible mechanism for the effects on hatchling quality by determining whether incubation temperature influences embryonic energy expenditure of wood ducks (Aix sponsa). Because avian embryos are ectothermic, we hypothesized that eggs incubated at higher temperatures would have greater energy expenditure at any given day of incubation. However, because eggs incubated at lower temperatures take longer to hatch than embryos incubated at higher temperatures, we hypothesized that the former would expend more energy during incubation. We incubated eggs at three temperatures (35.0°, 35.9°, and 37.0°C) that fall within the range of temperatures of naturally incubated wood duck nests. We then measured the respiration of embryos every 3 d during incubation, immediately after ducks externally pipped, and immediately after hatching. As predicted, embryos incubated at the highest temperature had the highest metabolic rates on most days of incubation, and they exhibited faster rates of development. Yet, because of greater energy expended during the hatching process, embryos incubated at the lowest temperature expended 20%-37% more energy during incubation than did embryos incubated at the higher temperatures. Slower developmental rates and greater embryonic energy expenditure of embryos incubated at the lowest temperature could contribute to their poor physiological performance as ducklings compared with ducklings that hatch from eggs incubated at higher temperatures.
近期对鸟类的研究表明，孵化温度会影响一系列对雏鸟发育和生存至关重要的特征。我们通过确定孵化温度是否会影响林鸳鸯（Aix sponsa）的胚胎能量消耗，来探究其对雏鸟质量产生影响的一种可能机制。由于鸟类胚胎是变温动物，我们推测在任何给定的孵化日，在较高温度下孵化的卵会有更高的能量消耗。然而，由于在较低温度下孵化的卵比在较高温度下孵化的胚胎需要更长时间才能孵化，我们推测前者在孵化过程中会消耗更多能量。我们将卵在自然孵化的林鸳鸯巢穴温度范围内的三个温度（35.0°、35.9°和37.0°C）下进行孵化。然后，在孵化期间、鸭子破壳后立即以及孵化后，每隔3天测量一次胚胎的呼吸情况。正如预测的那样，在最高温度下孵化的胚胎在大多数孵化日具有最高的代谢率，并且它们的发育速度更快。然而，由于在孵化过程中消耗了更多能量，在最低温度下孵化的胚胎在孵化期间比在较高温度下孵化的胚胎多消耗20% - 37%的能量。与从在较高温度下孵化的卵中孵出的雏鸭相比，在最低温度下孵化的胚胎发育速度较慢且胚胎能量消耗更大，这可能导致它们作为雏鸭的生理表现较差。
