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URA CNRS 243, Laboratoire de Biométrie, Génétique et Biologie des Populations, Université Claude Bernard Lyon I, 43, Bd du 11 novembre 1918, 69622, Villeurbanne Cedex, France.
Oecologia. 1993 Dec;96(3):383-390. doi: 10.1007/BF00317509.
In the chestnut weevil Curculio elephas, adult emergences spread over 3 or 4 years due to prolonged larval diapause in some individuals. Weevils with an extended diapause emerge, on the average, 1-10 days before those with simple diapause, but whatever the age of insects, emergences occur always from mid-August to early October. When the summer is dry, some adults cannot emerge because of the hardness of the soil. Emergence sucess of adults is smaller in females than in males. The result is that the sex ratio is female-biased before emergence and male-biased after. Summer drought cannot be predicted by the chestnut weevil, and when the soil is dry 27-78% of females cannot emerge and do not reproduce. The year after a summer drought, many reproducing females may emerge from larvae with prolonged diapause. These results suggest an evolutionary influence on the variability in diapause duration. Computer simulations and observations do not support the hypothesis that the main cause of variation in diapause length is the existence of several distinct genotypes within populations. On the contrary, our data strengthen the hypothesis for coin-flipping plasticity discussed in a previous paper.
在栗象Curculio elephas中，由于部分个体幼虫滞育期延长，成虫羽化会持续3到4年。滞育期延长的象鼻虫平均比滞育期简单的象鼻虫提前1至10天羽化，但无论昆虫年龄如何，羽化总是在8月中旬至10月初发生。夏季干燥时，一些成虫因土壤坚硬而无法羽化。成虫羽化成功率雌性低于雄性。结果是羽化前性别比偏向雌性，羽化后偏向雄性。栗象无法预测夏季干旱，当土壤干燥时，27%至78%的雌性无法羽化且无法繁殖。夏季干旱后的次年，许多滞育期延长的幼虫可能会羽化出繁殖雌性。这些结果表明进化对滞育期持续时间的变异性有影响。计算机模拟和观察结果不支持滞育长度变异的主要原因是种群内存在几种不同基因型这一假设。相反，我们的数据强化了前一篇论文中讨论的抛硬币式可塑性假设。
