Bird Predation and Foodplant Specificity in Closely Related Procryptic Insects
Bird Predation and Foodplant Specificity in Closely Related Procryptic Insects
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密切相关的原隐昆虫的鸟类捕食和食用植物特异性
DOI：
10.1086/282025
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发表时间：
1958
期刊：
影响因子：
--
通讯作者：
L. Brower
中科院分区：
文献类型：
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作者：
L. Brower
鸟类和F () OD在昆虫中的植物特异性：185个与它们一起出现在树干上，而不是单独出现（Kettlewell, 1956）。除了这些观察和实验之外，拉克还得出结论，已知大多数鸟类会专注于少数几种食物，即使它们偶尔也会吃其他食物。他还提供了证据，表明有些鸟类在专注于一种特定的昆虫猎物时，只会选择一定体型以上的个体。从这些发现中，我们或许可以得出这样的结论：鸟类捕食植食昆虫的行为是这样的：如果先前发现的食物外观相似且美味可口，那么发现具有特定形状、颜色、图案和大小的食物的可能性就会增加。事实上，根据Tinbergen的说法，在许多动物中都观察到“特定猎物发育”的现象。鸟类的这种行为在自然界中很容易导致密度依赖的捕食。其他可能增加捕食依赖于密度的可能性的因素是，已知一些鸟类将其食物狩猎活动限制在特定种类的树木上，也限制在这些树木的特定部分（Lack, MacArthur, 1958）。此外，许多昆虫只在有限的植物区域取食。最后，单个植物物种的个体之间的差异可能导致某些物种的昆虫集中，而另一些物种的昆虫缺乏或稀少（Varley, 1957; Brower, ms. in preparation）。从密切相关的原隐昆虫物种之间的竞争的角度来看，这些考虑是重要的，因为当新进化的物种在地理隔离的起源后第一次相遇时，它们通常在外观上相似。正如莫斯特勒（1935）和简·布劳尔（出版中）所表明的那样，各种雀形目鸟类经过训练，可以避开令人讨厌的昆虫，但它们也会一看到与自己相似的昆虫就拒绝。在这些实验的基础上，我们可以预测，自然界中的鸟常常不能把关系密切的一种昆虫与其他昆虫区分开来，也就是说，它会把它们都当作一个“视觉物种”。当新物种开始渗透到彼此的范围内时，就会有一种趋势，即每一种物种的数量都增加到单独发生的水平。因为鸟类通常无法区分不同的食物，所以在任何一种食物上绘制的搜索图像都将包括所有的食物，每个物种的有效密度将乘以以同一种食物为食的物种的数量。这样的综合密度可能会高到足以引发像德鲁伊特棒状毛虫那样的大规模捕食。通过这种方式，鸟类可以对每个物种的数量施加重要的控制，从而防止它们成为广泛的同域分布。但是，即使近亲物种的总密度太低，捕食者无法有效控制它们的种群规模，
BIRD) DREDATION AND F () OD PLANT SPECIFICITY IN INSECTS 185 ones were present with them on the tree trunks than if the harmonizing ones were alone (Kettlewell, 1956). In addition to the se observations and experiments, Lack concluded that most bird species are known to concentrate on a small number of food items even though they take others occasionally, and he also gave evidence that some birds, while concentrating on a particular species of insect prey, will only select individuals above a certain size. From these findings it is perhaps not unreasonable to generalize that the behavior of birds which e at phytophagous insects is such that the probability of discovering a food item of a particular shape, color-pattern, and size is increased if the one previously found is of similar appearance and is palatable. In fact, according to Tinbergen, the phenomenon of developing''of a specific prey has been observed in many animals. a" searching image This kind of behavior in birds could easily lead to density-dependent pre-dation in nature. Other factors which could increase the likelihood that the predation would be density-dependent are that some birds are known to restrict their food-hunting activities to particular species of trees, and to particular parts of these as well (Lack, MacArthur, 1958). Moreover, many insects restrict their feeding to limited regions of plants. And finally, differences between individuals of a single plant species can lead to a concentration of insects on some, and their absence or scarcity on others (Varley, 1957; Brower, ms. in preparation). The se considerations are important from the point of view of competition between closely related species of procryptic insects feeding together on the same plants because of the fact that when newly evolved species meet for the first time after their origin in geographic isolation they will often be similar in appearance. As Mostler (1935) and Jane Brower (in press) have shown, various passerine birds trained to avoid distasteful insects will also refuse on sight alone insects which bear a general resemblance to them. On the basis of these experiments it can be predicted that a bird in nature would often fail to distinguish one of the closely related species of insects from the others, that is, it would treat them all as one"" visual species.” When the new species began to penetrate the ranges of each other, there would be a tendency for each to increase its numbers up to the level where it occurred alone. Because the birds would usually fail to discriminate one from the others, a searching image developed on any one would include them all and the effective density of each individual species would be multiplied by the number of species feeding together on the same foodplants. This combined density might then be high enough to trigger heavy predation as in de Ruiter's stick caterpillars. In this way the birds could exert an important control on the numbers of each of the species present and thereby prevent them from becoming widely sympatric. But even if the combined density of the closely related species were too low for the predation to be effective in controlling their population sizes,