生命能量被快速消耗，最终导致英年早逝——这似乎是动物王国的魔咒。一只动物消耗越多能量，它的身体就会产生越多的自由基和不稳定、破坏细胞的分子，这样的分子过多便会缩短寿命。
然而，Glanville的豹纹蝶（庆网蛱蝶）似乎并没有遵循这个备忘录。当对这种有杂乱图案的昆虫的代谢速率进行测量时，研究者发现这些蝴蝶在飞行时耗费最多的能量，但也活得最长，无论它们是在实验室范围内还是被放飞到芬兰的草甸上。这些发现表明，氧化压力——自由基和有害分子的长期存在——与寿命之间的联系可能比之前想得更加复杂。
其全速飞行的能力表明，该蝴蝶很自然地拥有更好的形态——无论是通过更有营养的食物还是个体遗传实现的——来推翻高度新陈代谢的有害副作用。研究者上个月在《实验生物学杂志》的网站上发表了这一研究结果。不过他们也怀疑适应高性能飞行的蝴蝶是否可能已经进化到有办法在高速新陈代谢时保护自己。(生物谷Bioon.com)
doi: 10.1242/jeb.080739
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A long life in the fast lane: positive association between peak metabolic rate and lifespan in a butterfly
Kristjan Niitepõld1,* and Ilkka Hanski2
High peak metabolic may provide performance advantage, but it may also entail a physiological cost. A long-held assumption is that high mass-specific energy expenditure is associated with short lifespan. To examine the relationship between energy expenditure and lifespan we asked two questions. First, do individuals have a consistent rate of metabolism throughout their life? Second, is metabolic rate correlated with lifespan? We analysed the repeatability of measurements of resting (RMR) and peak flight metabolic rate (MRpeak) throughout the life of the Glanville fritillary butterfly (Melitaea cinxia). Measurements of MRpeak showed significant repeatability. Senescence occurred only shortly before death. RMR showed a U-shaped relationship with age and very low repeatability. Intraspecific association between metabolic rates and lifespan was tested under three conditions: in the laboratory, under field conditions, and in a laboratory experiment with repeated flight treatments. There was a significant correlation between MRpeak and lifespan in all three experiments, but the correlation was positive, not negative. RMR was not correlated with lifespan. Both MRpeak and lifespan may reflect physiological condition and be therefore positively correlated. Individuals with a large resource pool may be able to invest in mechanisms that slow down ageing. Individuals with high metabolic capacity may also possess adaptations against ageing. Molecular polymorphism in the gene phosphoglucose isomerase (Pgi) was significantly associated with both MRpeak and lifespan, and may have coevolved with defence mechanisms against senescence. Generalisations such as 'live fast, die young' may be too simple to explain the complex processes affecting ageing and lifespan.
