Monarch butterfly (Danaus plexippus) thermoregulatory behavior and adaptations for overwintering in Mexico
Monarch butterfly (Danaus plexippus) thermoregulatory behavior and adaptations for overwintering in Mexico
复制标题
墨西哥帝王蝶（Danaus plexippus）的体温调节行为和越冬适应
作者：
A. R. Masters;S. Malcolm;L. Brower
北美东部的帝王蝶每年秋天迁徙到墨西哥中部的高海拔栖息地，必须避免冰冻、干燥、热应激和捕食，同时利用不可再生的脂肪储备至少90天。生存涉及获得热量的形态和行为，其中温度调节起核心作用。颤抖产生的热量使胸腔温度上升到足以让蝴蝶爬上植被进行日光浴，在那里它们迅速升温到飞行阈值(°12.7°-16.0°C)。在部分多云的天气里，颤抖和晒太阳也可以达到或保持飞行温度。这两种行为都延缓了胸腔温度下降到飞行阈值以下的时间，以及随之而来的热陷阱，要么是在其他帝王蜂群下面的地面上，要么是当蝴蝶在水或花蜜来源时。因此，帝王蝶是第一只颤抖被证明具有重大生态重要性的蝴蝶。在热谱的另一端，在这种高度的强烈日照下，在低至9度的环境温度下，会导致迅速变暖。为了避免过热和快速耗尽，蝴蝶采取最小化总和的姿势，或者飞出暴晒的集群，在群落上方滑行，将热量流失到寒冷的环境中。计算表明，很大一部分蝴蝶死于脂肪储备的耗尽。维持较低的体温以保存血脂是候鸟选择这些高山森林作为其越冬栖息地的主要原因之一。
Monarch butterflies from eastern North America migrate each fall to high altitude habitats in central Mexico and must avoid freezing, desiccation, heat stress, and predation while drawing on unrenewable lipid reserves for at least 90 d. Survival involves a heat—gaining morphology and behaviors in which thermoregulation plays a central role. Heat production by shivering permits raising of thoracic temperatures sufficiently for the butterflies to crawl up vegetation to sun—bask where they warm rapidly to flight threshold (°12.7°—16.0°C). Shivering and basking can also achieve or maintain flight temperature during partly cloudly weather. Both behaviors delay the decline of thoracic temperatures below flight threshold and consequent thermal trapping either on the ground beneath clusters of other monarchs, or while the butterflies are at water or nectar sources. The monarch thus is the first butterfly in which shivering has been shown to be of major ecological importance. At the other end of the thermal spectrum, basking in the intense insolation at this lattitude causes rapid warming at ambient temperatures as low as 9°. To avoid overheating and rapid depletion, the butterflies adopt sum—minimizing postures or fly out of insolated clusters and glide above the colony, losing heat to the cold ambient. Calculations suggest that a large proportion of the butterfies dies from depleting lipid stores. Maintenance of low body temperatures to conseve lipids is one of the major reasons why migrant monarchs select these high mountain forest as their overwinterin habitat.