Plasticity constrained: over-generalized induction cues cause maladaptive phenotypes
Plasticity constrained: over-generalized induction cues cause maladaptive phenotypes
复制标题
可塑性受限：过度概括的诱导线索导致适应不良表型
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
T. DeWitt
中科院分区：
文献类型：
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作者：
R. Langerhans;T. DeWitt
表型可塑性的适应值取决于表型与环境之间的匹配程度。这种匹配在一定程度上取决于生物体对环境状态的识别能力(例如，是否存在特定的捕食者)。为了检验生物利用线索诱导防御表型的特异性，我们饲养了淡水蜗牛Physella virgata，分别与软体动物和非软体动物太阳鱼(Lepomis Bluellus、L.gibBosus、L.Macchirus、L.megalotis、L.microlophus、Micropterus salmoides)一起饲养。无论是哪一类捕食者饲养蜗牛，蜗牛都表现出两种诱导反应：(1)生长减少和(2)发育出圆圆的壳。生长减慢通常是由于捕食者的回避行为造成的，因此在含有软体动物的环境中与净生存效益有关。圆圆的贝壳增加了耐压性，因此增加了处理时间和对软体动物太阳鱼的拒绝率。尽管这些对软体动物物种的反应具有适应性，但对非软体动物的不必要反应是不适应的。生长减少限制了繁殖力，并阻止蜗牛获得大多数捕食者的大小避难所。圆形的贝壳增加了对进入贝壳的捕食者的脆弱性，后者通常比粉碎贝壳的捕食者更常见。因此，诱导的反应需要成本，但在存在非软体动物的太阳鱼时不会带来任何好处。缺乏使用线索的特异性(例如，所有太阳鱼都被同等对待)可能是表型可塑性进化的一个主要制约因素。此外，这些诱导的反应可能产生性状介导的间接效应，这些效应在整个食物链中级联。
The adaptive value of phenotypic plasticity depends upon the degree of match achieved between phenotype and environment. This match is governed in part by how well organisms discern environmental states (e.g. presence or absence of particular predators). To examine the specificity with which organisms use cues to induce defensive phenotypes, we raised freshwater snails, Physella virgata, with either molluscivorous or non-molluscivorous sunfish species (Lepomis cyanellus, L. gibbosus, L. macrochirus, L. megalotis, L. microlophus, Micropterus salmoides). Regardless of the predator class with which they were raised, snails exhibited two induced responses: (1) reduced growth and (2) development of rotund shells. Reduced growth typically results from predator avoidance behaviours and so is associated with a net survival benefit in environments containing molluscivores. Rotund shells increase crush resistance and so increase both handling time and rejection rates by molluscivorous sunfish. Despite the adaptive nature of these responses to molluscivorous species, responding unnecessarily to non-molluscivores is maladaptive. Growth reduction limits fecundity and prevents snails from attaining size refugia for most predators. Rotund shells increase vulnerability to shell-entry predators, which are typically more common than shell-crushing predators. Thus the induced responses entail costs but award no advantages in the presence of non-molluscivorous sunfish. Lack of specificity in use of cues (e.g. all sunfish treated alike) may be a major constraint on the evolution of phenotypic plasticity. Furthermore, these induced responses may produce trait-mediated indirect effects that cascade throughout the food web.