The cost of melanization: Butterfly wing coloration under environmental stress
The cost of melanization: Butterfly wing coloration under environmental stress
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DOI：
10.1111/j.0014-3820.2004.tb01651.x
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发表时间：
2004-02-01
期刊：
影响因子：
3.3
通讯作者：
Lens, L
中科院分区：
文献类型：
--
作者：
Talloen, W;Van Dyck, H;Lens, L
进化研究通常侧重于对特定环境条件的适应，因此往往忽略了可能的限制的作用。在这里，我们集中在一个satyrine蝴蝶Pararge aegeria的背翅黑化的变化的情况下。由于黑色素是一种复杂的聚合物，如果环境条件限制了资源预算，其合成可能会受到限制。这一假设进行了测试，通过比较黑化之间的蝴蝶，作为幼虫的宿主草经历不同的干旱胁迫处理。治疗差异进行了验证，在宿主植物（氮，碳酸盐和水含量）和蝴蝶（生活史特征：生存，发育时间，成熟时的大小）的水平。黑化率以背翅基部区域的平均灰度值来衡量。这个区域靠近胸部，已知对于晒太阳以调节体温具有重要的功能。干旱胁迫的寄主植物上饲养的个人开发苍白的翅膀，和黑暗的个人发展缓慢，不稳定的波动不对称的水平估计。这些结果提供了证据，黑色素确实是昂贵的合成，并在环境质量的差异可以诱导翅黑化的表型变异。因此，研究处理的空间和/或时间模式的变化，在翅膀黑化不应该只集中在适应性的解释，而是在特定的环境条件下的成本效益平衡。
Evolutionary studies typically focus on adaptations to particular environmental conditions, thereby often ignoring the role of possible constraints. Here we focus on the case of variation in dorsal wing melanization in a satyrine butterfly Pararge aegeria. Because melanin is a complex polymer, its synthesis may be constrained if ambient conditions limit the resource budget. This hypothesis was tested by comparing melanization among butterflies that fed as larvae on host grasses experiencing different drought-stress treatments. Treatment differences were validated both at the level of the host plant (nitrogen, carbonate, and water content) and of the butterfly (life-history traits: survival, development time, and size at maturity). Melanization rate was measured as average gray value of the basal dorsal wing area. This area, close to the thorax, is known to be functionally significant for basking in order to thermoregulate. Individuals reared on drought-stressed host plants developed paler wings, and development of darker individuals was slower and less stable as estimated by their level of fluctuating asymmetry. These results provide evidence that melanin is indeed costly to synthesize, and that differences in environmental quality can induce phenotypic variation in wing melanization. Therefore, studies dealing with spatial and/or temporal patterns of variation in wing melanization should not focus on adaptive explanations alone, but rather on a cost-benefit balance under particular sets of environmental conditions.