Phenotypic convergence along a gradient of predation risk
Phenotypic convergence along a gradient of predation risk
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DOI：
10.1098/rspb.2010.1989
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发表时间：
2011-06-07
影响因子：
4.7
通讯作者：
Beckerman, A. P.
中科院分区：
文献类型：
--
作者：
Dennis, S. R.;Carter, Mauricio J.;Beckerman, A. P.
生态学中一个长期存在的问题是，表型可塑性（而不是选择本身）是否是种群间表型变异的原因。可塑性可以增加或减少变异，但大多数先前的研究仅限于使用单变量反应规范评估的单一种群、单一性状和少数环境。在这里，我们检查了具有不同捕食历史的两个遗传上不同的水蚤种群，沿着两个种群共有的捕食者（Chaoborus）捕食风险的精细尺度梯度，量化了捕食者诱导的 11 个性状的可塑性。我们通过表型轨迹分析（PTA）实验表征多变量反应范数，检验了可塑性可能导致不同群体之间表型趋同的假设。单变量分析表明，所有基因型在成熟时都会增加年龄和体型，并投资于防御尖峰（颈牙），但未能定量描述整个生物体的反应。相比之下，PTA 量化并限定了生物体针对选择压力而采取的表型策略。我们证明，在整个生物体水平上，两个种群在没有捕食的情况下占据不同的表型空间区域，但随着捕食威胁的增加在表型空间中趋同。
A long-standing question in ecology is whether phenotypic plasticity, rather than selection per se, is responsible for phenotypic variation among populations. Plasticity can increase or decrease variation, but most previous studies have been limited to single populations, single traits and a small number of environments assessed using univariate reaction norms. Here, examining two genetically distinct populations of Daphnia pulex with different predation histories, we quantified predator-induced plasticity among 11 traits along a fine-scale gradient of predation risk by a predator (Chaoborus) common to both populations. We test the hypothesis that plasticity can be responsible for convergence in phenotypes among different populations by experimentally characterizing multivariate reaction norms with phenotypic trajectory analysis (PTA). Univariate analyses showed that all genotypes increased age and size at maturity, and invested in defensive spikes (neckteeth), but failed to quantitatively describe whole-organism response. In contrast, PTA quantified and qualified the phenotypic strategy the organism mobilized against the selection pressure. We demonstrate, at the whole-organism level, that the two populations occupy different areas of phenotypic space in the absence of predation but converge in phenotypic space as predation threat increases.