ADAPTIVE PLASTICITY OF EGG SIZE IN RESPONSE TO COMPETITION IN THE COWPEA WEEVIL, CALLOSOBRUCHUS-MACULATUS (COLEOPTERA, BRUCHIDAE)
ADAPTIVE PLASTICITY OF EGG SIZE IN RESPONSE TO COMPETITION IN THE COWPEA WEEVIL, CALLOSOBRUCHUS-MACULATUS (COLEOPTERA, BRUCHIDAE)
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DOI：
10.1007/bf00333313
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发表时间：
1995-04-01
期刊：
影响因子：
2.7
通讯作者：
KAWECKI, TJ
中科院分区：
文献类型：
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作者：
KAWECKI, TJ
生活史理论预测，当后代预期经历激烈竞争时，应该产生更大的繁殖体。这项研究测试了女性豇豆象鼻虫是否响应高幼虫或成人密度产生更大的鸡蛋。在一个分裂育雏设计，我测量了密度的影响所经历的女性在其幼虫阶段（1与4-6幼虫/豇豆）的大小产生的鸡蛋刚刚出现后。然后将雌性以低成虫密度（1只雌性+1只雄性/小瓶）或高成虫密度（10只雌性+10只雄性）饲养2天，并测试该成虫密度处理对随后产卵大小的影响。我测量了卵的长度和宽度，以及幼虫形成的入口通道的直径，这可以被视为幼虫大小的粗略测量。女性经历了高成人密度随后奠定了略宽的鸡蛋比那些保持在低密度。这种差异虽然很小（根据所用统计模型，校正女性体重和家庭影响后约为1-4%），但具有统计学显著性，并且对统计模型的改变具有鲁棒性。这可能是一个残余的较大的塑料反应的鸡蛋大小的竞争，已成为侵蚀在许多代在高密度的实验室培养。卵的长度和入口通道的直径没有差异。刚出现后，由女性在高幼虫密度饲养的鸡蛋也往往比那些没有竞争对手的女性所产生的更广泛。然而，这种影响只是轻微的，并且对统计模型敏感。卵长、卵宽和入口通道直径均随雌虫体重的增加而增加，随雌虫日龄的增加而减小。隧道直径与卵长和卵宽均呈正相关，但卵宽的影响较大。
Life history theory predicts that larger propagules should be produced when the offspring are expected to experience intense competition. This study tested whether female cowpea weevils responded to high larval or adult density by producing larger eggs. In a split-brood design I measured the effect of density experienced by females at their larval stage (1 vs. 4-6 larvae/cowpea) on the size of eggs produced just after emergence. The females were then kept either at low adult density (1 female+1 male per vial), or at high adult density (10 females+10 males) for 2 days, and tested for the effect of this adult density treatment on the size of eggs laid subsequently. I measured egg length and width, as well as the diameter of the entrance tunnel made by the larva, which can be regarded as a crude measure of larval size. Females that experienced high adult density subsequently laid slightly wider eggs than those kept at low density. This difference, albeit small (about 1-4% after correction for female weight and the effect of family, depending on the statistical model used), was statistically significant and robust to alterations of the statistical model. It may be a remnant of a larger plastic response of egg size to competition that has become eroded during many generations in high-density laboratory cultures. There was no difference in egg length or the diameter of the entrance tunnel. Eggs laid just after emergence by females reared at high larval density also tended to be wider than those produced by females that had no competitors. This effect was only marginally significant, however, and sensitive to the statistical model. Both egg length and width and the diameter of the entrance tunnel increased with female weight and decreased with female age. The tunnel diameter was positively correlated with both egg length and width, but the effect of width was larger.