Odum School of Ecology, The University of Georgia, Athens, Georgia 30602, USA.
Evolution. 2010 Apr 1;64(4):1018-28. doi: 10.1111/j.1558-5646.2010.00946.x. Epub 2010 Jan 11.
The demands of long-distance flight represent an important evolutionary force operating on the traits of migratory species. Monarchs are widespread butterflies known for their annual migrations in North America. We examined divergence in wing morphology among migratory monarchs from eastern and western N. America, and nonmigratory monarchs in S. Florida, Puerto Rico, Costa Rica, and Hawaii. For the three N. American populations, we also examined monarchs reared in four common environment experiments. We used image analysis to measure multiple traits including forewing area and aspect ratio; for laboratory-reared monarchs we also quantified body area and wing loading. Results showed wild monarchs from all nonmigratory populations were smaller than those from migratory populations. Wild and captive-reared eastern monarchs had the largest and most elongated forewings, whereas monarchs from Puerto Rico and Costa Rica had the smallest and roundest forewings. Eastern monarchs also had the largest bodies and high measures of wing loading, whereas western and S. Florida monarchs had less elongated forewings and smaller bodies. Among captive-reared butterflies, family-level effects provided evidence that genetic factors contributed to variation in wing traits. Collectively, these results support evolutionary responses to long-distance flight in monarchs, with implications for the conservation of phenotypically distinct wild populations.
长途飞行的需求代表了一种重要的进化力量，对迁徙物种的特征产生了影响。帝王蝶是一种分布广泛的蝴蝶，以其在北美的年度迁徙而闻名。我们研究了来自北美东部和西部的迁徙帝王蝶、来自佛罗里达州南部、波多黎各、哥斯达黎加和夏威夷的非迁徙帝王蝶之间的翅膀形态差异。对于这三个北美种群，我们还研究了在四种常见环境实验中饲养的帝王蝶。我们使用图像分析来测量多个特征，包括前翅面积和长宽比；对于实验室饲养的帝王蝶，我们还量化了身体面积和翅膀负荷。结果表明，所有非迁徙种群的野生帝王蝶都比迁徙种群的小。来自所有非迁徙种群的野生和圈养帝王蝶的前翅最大且最狭长，而来自波多黎各和哥斯达黎加的帝王蝶的前翅最小且最圆。东部帝王蝶的身体也最大，翅膀负荷也很高，而西部和佛罗里达州南部的帝王蝶的前翅则不那么狭长，身体也较小。在圈养蝴蝶中，家族水平的影响提供了证据，表明遗传因素导致了翅膀特征的变异。总的来说，这些结果支持了帝王蝶对长途飞行的进化反应，这对保护表型独特的野生种群具有重要意义。
